A merchant point-of-sale (“POS”) system architecture is provided. Systems and methods are provided for enabling free form rewards in a custom rewards transaction at a POS terminal. A custom rewards transaction may be a transaction in which a customer opts-in to a merchant-funded rewards (“MFR”) program. The merchant may offer rewards in the MFR program based on location and customer data. The merchant may offer rewards that promote customer behaviors that are advantageous to the merchant. Opting-in to the MFR program may terminate the customer's default enrollment in a conventional issuer-bank funded rewards program.