A system for providing supplementary product sales is provided in which a central controller receives a purchase from a card authorization terminal. The purchase includes at least one purchase parameter, such as a customer account identifier, product identifiers for specifying items purchased or product price. The central controller determines a supplementary product to offer that is based on the at least one purchase parameter. A product identifier for specifying the supplementary product is transmitted to the card authorization terminal, where the customer chooses whether to accept the offered supplementary product. The card authorization terminal generates and transmits to the central controller a selection signal indicative of whether the supplementary product is accepted. If the selection signal indicates that the supplementary product is accepted, the central controller adjusts a balance of a financial account in dependence on an adjustment value associated with the supplementary product.