In some embodiments, a method and apparatus involve: providing a plurality of products that are each associated with a respective radio frequency identification tag; using radio frequency identification technology to automatically identify specific products in a group of products collected by a shopper; and evaluating whether or not to obtain payment from the shopper based on the radio frequency identification of products in the group. Based on the result of the evaluation, either payment is obtained from the shopper on the basis of the radio frequency identification of products in the group, or else the products in the group are audited, and then payment is obtained on the basis of the products identified by the audit.