function calcTax($subTotal, $storeId)
 {
     $tax = new Tax();
     $rs = $tax->taxRate($storeId);
     if (isset($rs[0])) {
         $taxRate = $rs[0]['rate'];
         return number_format(floatval($subTotal) * floatval($taxRate / 100), 2, '.', ' ');
     } else {
         return number_format(0, 2, '.', ' ');
     }
 }