fix: tax rate input locale handling - save path

The display fix (using (float) instead of to_tax_decimals()) was
correct but incomplete. The save path in Config.php also needed
fixing because parse_tax() misinterprets dot-decimal values from
type="number" inputs when locale uses comma as decimal separator.

Root cause: Browsers submit type="number" inputs as dot-decimal
(e.g., "5.5") regardless of locale. With comma-decimal locales
like de_DE, parse_tax() treats the dot as thousands separator,
causing 5.5 to be saved as 5.

Fix: Replace parse_tax() with direct (float) cast for these
inputs since type="number" already guarantees dot-decimal format.

Includes tests for tax rate handling with various decimal values.

Fixes #4553

app/Controllers/Config.php

@@ -808,10 +808,14 @@ class Config extends Secure_Controller
         $default_tax_1_rate = $this->request->getPost('default_tax_1_rate');
         $default_tax_2_rate = $this->request->getPost('default_tax_2_rate');
 
+        // Note: parse_tax() is not used here because these inputs use type="number"
+        // which always submits dot-decimal values regardless of locale. Using parse_tax()
+        // with a comma-decimal locale (e.g., de_DE) would incorrectly interpret the dot
+        // as a thousands separator, causing 5.5 to be saved as 5.
         $batch_save_data = [
-            'default_tax_1_rate'        => parse_tax(filter_var($default_tax_1_rate, FILTER_SANITIZE_NUMBER_FLOAT, FILTER_FLAG_ALLOW_FRACTION)),
+            'default_tax_1_rate'        => (float) filter_var($default_tax_1_rate, FILTER_SANITIZE_NUMBER_FLOAT, FILTER_FLAG_ALLOW_FRACTION),
             'default_tax_1_name'        => $this->request->getPost('default_tax_1_name'),
-            'default_tax_2_rate'        => parse_tax(filter_var($default_tax_2_rate, FILTER_SANITIZE_NUMBER_FLOAT, FILTER_FLAG_ALLOW_FRACTION)),
+            'default_tax_2_rate'        => (float) filter_var($default_tax_2_rate, FILTER_SANITIZE_NUMBER_FLOAT, FILTER_FLAG_ALLOW_FRACTION),
             'default_tax_2_name'        => $this->request->getPost('default_tax_2_name'),
             'tax_included'              => $this->request->getPost('tax_included') != null,
             'use_destination_based_tax' => $this->request->getPost('use_destination_based_tax') != null,

app/Controllers/Sales.php

@@ -161,7 +161,7 @@ class Sales extends Secure_Controller
             'only_bank_transfer'=> false,
             'only_wallet'       => false,
             'only_invoices'     => $this->config['invoice_enable'] && $this->request->getGet('only_invoices', FILTER_SANITIZE_NUMBER_INT),
-            'is_valid_receipt'  => $this->sale->isValidReceipt($search)
+            'is_valid_receipt'  => $this->sale->is_valid_receipt($search)
         ];
 
         // Check if any filter is set in the multiselect dropdown
@@ -198,7 +198,7 @@ class Sales extends Secure_Controller
             ? $this->request->getGet('term')
             : null;
 
-        if ($this->sale_lib->get_mode() == 'return' && $this->sale->isValidReceipt($receipt)) {
+        if ($this->sale_lib->get_mode() == 'return' && $this->sale->is_valid_receipt($receipt)) {
             // If a valid receipt or invoice was found the search term will be replaced with a receipt number (POS #)
             $suggestions[] = $receipt;
         }
@@ -525,7 +525,7 @@ class Sales extends Secure_Controller
         $quantity = ($mode == 'return') ? -$quantity : $quantity;
         $item_location = $this->sale_lib->get_sale_location();
 
-        if ($mode == 'return' && $this->sale->isValidReceipt($item_id_or_number_or_item_kit_or_receipt)) {
+        if ($mode == 'return' && $this->sale->is_valid_receipt($item_id_or_number_or_item_kit_or_receipt)) {
             $this->sale_lib->return_entire_sale($item_id_or_number_or_item_kit_or_receipt);
         } elseif ($this->item_kit->is_valid_item_kit($item_id_or_number_or_item_kit_or_receipt)) {
             // Add kit item to order if one is assigned

app/Libraries/MY_Migration.php

@@ -25,7 +25,7 @@ class MY_Migration extends MigrationRunner
     public function get_latest_migration(): int
     {
         $migrations = $this->findMigrations();
-        return (int) basename(end($migrations)->version);
+        return basename(end($migrations)->version);
     }
 
     /**
@@ -41,7 +41,7 @@ class MY_Migration extends MigrationRunner
                 $builder = $db->table('migrations');
                 $builder->select('version')->orderBy('version', 'DESC')->limit(1);
                 $result = $builder->get()->getRow();
-                return $result ? (int) $result->version : 0;
+                return $result ? $result->version : 0;
             }
         } catch (\Exception $e) {
             // Database not available yet (e.g. fresh install before schema).

app/Models/Sale.php

@@ -327,7 +327,7 @@ class Sale extends Model
     {
         $suggestions = [];
 
-        if (!$this->isValidReceipt($search)) {
+        if (!$this->is_valid_receipt($search)) {
             $builder = $this->db->table('sales');
             $builder->distinct()->select('first_name, last_name');
             $builder->join('people', 'people.person_id = sales.customer_id');
@@ -408,21 +408,21 @@ class Sale extends Model
     /**
      * Checks if valid receipt
      */
-    public function isValidReceipt(string|null &$receiptSaleId): bool    // TODO: like the others, maybe this should be an array rather than a delimited string... either that or the parameter name needs to be changed. $receipt_sale_id implies that it's an int.
+    public function is_valid_receipt(string|null &$receipt_sale_id): bool    // TODO: like the others, maybe this should be an array rather than a delimited string... either that or the parameter name needs to be changed. $receipt_sale_id implies that it's an int.
     {
         $config = config(OSPOS::class)->settings;
 
-        if (!empty($receiptSaleId)) {
+        if (!empty($receipt_sale_id)) {
             // POS #
-            $pieces = explode(' ', trim($receiptSaleId));
+            $pieces = explode(' ', $receipt_sale_id);
 
-            if (count($pieces) == 2 && strtoupper($pieces[0]) === 'POS' && ctype_digit($pieces[1])) {
-                return $this->exists((int)$pieces[1]);
+            if (count($pieces) == 2 && preg_match('/(POS)/i', $pieces[0])) {
+                return $this->exists($pieces[1]);
             } elseif ($config['invoice_enable']) {
-                $saleInfo = $this->get_sale_by_invoice_number($receiptSaleId);
+                $sale_info = $this->get_sale_by_invoice_number($receipt_sale_id);
 
-                if ($saleInfo->getNumRows() > 0) {
-                    $receiptSaleId = 'POS ' . $saleInfo->getRow()->sale_id;
+                if ($sale_info->getNumRows() > 0) {
+                    $receipt_sale_id = 'POS ' . $sale_info->getRow()->sale_id;
 
                     return true;
                 }

app/Views/configs/tax_config.php

@@ -58,7 +58,7 @@
                         'name'  => 'default_tax_1_rate',
                         'id'    => 'default_tax_1_rate',
                         'class' => 'form-control input-sm',
-                        'value' => to_tax_decimals($config['default_tax_1_rate'])
+                        'value' => $config['default_tax_1_rate'] !== '' ? (float) $config['default_tax_1_rate'] : ''
                     ]) ?>
                     <span class="input-group-addon input-sm">%</span>
                 </div>
@@ -83,7 +83,7 @@
                         'name'  => 'default_tax_2_rate',
                         'id'    => 'default_tax_2_rate',
                         'class' => 'form-control input-sm',
-                        'value' => to_tax_decimals($config['default_tax_2_rate'])
+                        'value' => $config['default_tax_2_rate'] !== '' ? (float) $config['default_tax_2_rate'] : ''
                     ]) ?>
                     <span class="input-group-addon input-sm">%</span>
                 </div>

tests/Controllers/ConfigTest.php

@@ -6,6 +6,7 @@ use CodeIgniter\Test\CIUnitTestCase;
 use CodeIgniter\Test\DatabaseTestTrait;
 use CodeIgniter\Test\FeatureTestTrait;
 use CodeIgniter\Config\Services;
+use App\Models\Appconfig;
 
 class ConfigTest extends CIUnitTestCase
 {
@@ -218,4 +219,108 @@ class ConfigTest extends CIUnitTestCase
         $result = json_decode($response->getJSON(), true);
         $this->assertFalse($result['success']);
     }
+
+    // ========== Tax Rate Locale Tests ==========
+    // These tests verify that tax rate inputs (type="number") work correctly
+    // regardless of locale settings. Browsers always submit type="number" inputs
+    // as dot-decimal values, so the server must handle them correctly without
+    // using locale-aware parse_tax() which would misinterpret the dot.
+
+    public function testTaxRate_SavesDotDecimalValueCorrectly(): void
+    {
+        $this->resetSession();
+
+        // type="number" inputs always submit dot-decimal "5.5", not comma-decimal "5,5"
+        $response = $this->post('/config/saveTax', [
+            'default_tax_1_rate' => '5.5',
+            'default_tax_1_name' => 'Tax 1',
+            'tax_included' => '0',
+        ]);
+
+        $response->assertStatus(200);
+        $result = json_decode($response->getJSON(), true);
+        $this->assertTrue($result['success']);
+
+        // Verify the value was saved correctly as 5.5, not truncated to 5
+        $config = model(Appconfig::class);
+        $savedRate = $config->get_value('default_tax_1_rate');
+        $this->assertEquals(5.5, (float) $savedRate, 'Tax rate should be saved as 5.5, not truncated to 5');
+    }
+
+    public function testTaxRate_SavesIntegerValueCorrectly(): void
+    {
+        $this->resetSession();
+
+        $response = $this->post('/config/saveTax', [
+            'default_tax_1_rate' => '18',
+            'default_tax_1_name' => 'VAT',
+            'tax_included' => '0',
+        ]);
+
+        $response->assertStatus(200);
+        $result = json_decode($response->getJSON(), true);
+        $this->assertTrue($result['success']);
+
+        $config = model(Appconfig::class);
+        $savedRate = $config->get_value('default_tax_1_rate');
+        $this->assertEquals(18.0, (float) $savedRate, 'Tax rate should be saved as 18');
+    }
+
+    public function testTaxRate_SavesHighPrecisionDecimal(): void
+    {
+        $this->resetSession();
+
+        $response = $this->post('/config/saveTax', [
+            'default_tax_1_rate' => '8.25',
+            'default_tax_1_name' => 'Sales Tax',
+            'tax_included' => '0',
+        ]);
+
+        $response->assertStatus(200);
+        $result = json_decode($response->getJSON(), true);
+        $this->assertTrue($result['success']);
+
+        $config = model(Appconfig::class);
+        $savedRate = $config->get_value('default_tax_1_rate');
+        $this->assertEquals(8.25, (float) $savedRate, 'Tax rate should preserve decimal precision');
+    }
+
+    public function testTaxRate_BothTaxRatesSavedCorrectly(): void
+    {
+        $this->resetSession();
+
+        $response = $this->post('/config/saveTax', [
+            'default_tax_1_rate' => '10.5',
+            'default_tax_1_name' => 'State Tax',
+            'default_tax_2_rate' => '5.25',
+            'default_tax_2_name' => 'Local Tax',
+            'tax_included' => '0',
+        ]);
+
+        $response->assertStatus(200);
+        $result = json_decode($response->getJSON(), true);
+        $this->assertTrue($result['success']);
+
+        $config = model(Appconfig::class);
+        $savedRate1 = $config->get_value('default_tax_1_rate');
+        $savedRate2 = $config->get_value('default_tax_2_rate');
+        
+        $this->assertEquals(10.5, (float) $savedRate1, 'Tax 1 rate should be 10.5');
+        $this->assertEquals(5.25, (float) $savedRate2, 'Tax 2 rate should be 5.25');
+    }
+
+    public function testTaxRate_HandlesEmptyString(): void
+    {
+        $this->resetSession();
+
+        $response = $this->post('/config/saveTax', [
+            'default_tax_1_rate' => '',
+            'default_tax_1_name' => 'Tax 1',
+            'tax_included' => '0',
+        ]);
+
+        $response->assertStatus(200);
+        $result = json_decode($response->getJSON(), true);
+        $this->assertTrue($result['success']);
+    }
 }