Fix rounding method for specific price reductions in Product class

Updated the rounding method for prices with specific reductions from Tools::ceilf to Tools::ps_round to ensure consistent pricing behavior across the application.

classes/Product.php

@@ -3957,7 +3957,7 @@ class ProductCore extends ObjectModel
 
         // Zaokrąglanie w górę tylko gdy mamy redukcję
         if ($specific_price && $specific_price['reduction'] > 0) {
-          $price = Tools::ceilf($price);
+          $price = Tools::ps_round($price);
         }
 
         // Group reduction