Complex Conditional Statements - 08. Trade Comissions

$town = ucfirst(strtolower(readline()));
$sales = floatval(readline());
$comission = null;

switch ($town) {
    case "Sofia":
        switch ($sales) {
            case ($sales >= 0 && $sales <= 500):
                $comission = ($sales * 5) / 100;
                break;
            case ($sales > 500 && $sales <= 1000):
                $comission = ($sales * 7) / 100;
                break;
            case ($sales > 1000 && $sales <= 10000):
                $comission = ($sales * 8) / 100;
                break;
            case ($sales > 10000):
                $comission = ($sales * 12) / 100;
                break;
            default:
        echo "error";
        exit(0);
        }
        break;
    case "Varna":
        switch ($sales) {
            case ($sales >= 0 && $sales <= 500):
                $comission = ($sales * 4.5) / 100;
                break;
            case ($sales > 500 && $sales <= 1000):
                $comission = ($sales * 7.5) / 100;
                break;
            case ($sales > 1000 && $sales <= 10000):
                $comission = ($sales * 10) / 100;
                break;
            case ($sales > 10000):
                $comission = ($sales * 13) / 100;
                break;
            default:
        echo "error";
        exit(0);
        }
        break;
    case "Plovdiv":
        switch ($sales) {
            case ($sales >= 0 && $sales <= 500):
                $comission = ($sales * 5.5) / 100;
                break;
            case ($sales > 500 && $sales <= 1000):
                $comission = ($sales * 8) / 100;
                break;
            case ($sales > 1000 && $sales <= 10000):
                $comission = ($sales * 12) / 100;
                break;
            case ($sales > 10000):
                $comission = ($sales * 14.5) / 100;
                break;
            default:
        echo "error";
        exit(0);
        }
        break;
    default:
        echo "error";
        exit(0);
}
if(!empty($comission)){
    echo number_format($comission, 2, ".", "");
}