Call FlexWin with the "voucher" parameter, and the list of payment methods will include vouchers. If selected, the user is prompted to enter the voucher code, she has received. Depending on the type of voucher, the original amount is reduced by either a fixed amount or a percentage, and the customer is then asked to only pay the remainder. Customers may only use one voucher per payment.
Note: Vouchers cannot be used along with split payments.