Preisrechner: Rappenrundung im Backend und Rabatt-Rechner im Web

agentd task ad07191c406d4ea496b0b18db826651e

src/Prices/PriceCalculator.cs

@@ -16,6 +16,8 @@ public static class PriceCalculator
             throw new ArgumentOutOfRangeException(nameof(discountPercent), "A discount is between 0 and 100 percent.");
         }
 
-        return price - discountPercent;
+        var discounted = price * (1 - discountPercent / 100m);
+        // Swiss rounding (Rappenrundung): round to the nearest 0.05
+        return Math.Round(discounted / 0.05m, MidpointRounding.ToEven) * 0.05m;
     }
 }