/**
  *     calculate taxes
  * @access        public
  * @param float|int $grand_total
  * @return        array
  */
 public static function calculate_taxes($grand_total = 0)
 {
     // create Ticket Price object from grand total and pass to constructor
     $taxes = new self(new EE_Total($grand_total, 'Sub Total'));
     return $taxes->get_taxes();
 }