Abstract: An interface device fits between a point-of-sale terminal and a peripheral element, for example, the UPC scanner, to permit a rapid checkout of groceries or the like by simulating rapid scanning of a stored grocery list accumulated by a consumer in a roaming checkout through the store. The consumer scans items as he or she shops to create the stored grocery list. A promotional system for providing coupons at the point of purchase decision and the novel method of handling items that need to be weighed are also provided.