"Coupon" Functionality in Order Management + Pricing

Consider the following scenario:

1) Unregistered customer makes a purchase in a retail store

2) Purchase Order is uploaded to Siebel (Order is not associated with any registered loyalty member or any contact)

3) Based on the information in Order (Order  Sum, Order Line Items), the discount is calculated, but this discount is not applied to the current order, it must be available for customer in the next purchase.  After discount calculation procedure, some sort of ‘coupon’ must be issued (‘coupon’ or ‘voucher’ , ‘certificate’, ‘promotion code’, etc.), this ‘coupon’ contains information about discount for next purchase. Unregistered customer is able to use this ‘coupon’ during the next purchase in a retail store.