A system and method for retail inventory checkout in which the customer selects items from the item shelves and as an item is taken from the shelf, the customer employs an input device, such as a portable data terminal, a smart phone provided with a store application or other suitable device that communicates with the store network, to identify the item either by scanning the optical code on the item or by other means, and then once scanned, the item is added to the purchase list and then placed in a shopping cart, basket or other container. Once item selection is completed, the customer proceeds to a point of sale (POS) or pay station and puts the cart onto a weigh scale whereby the total weight of the cart with the items included (measured total weight) is measured by the weigh scale and the net weight of the items in the cart (calculated by subtracting the weight of the cart from the measured total weight) is compared to a theoretic weight of the items as calculated by the store system using the weight information of the items present in the store database. Based on the result of the comparison, the store system either approves the transaction, whereby the customer then pays for the transaction and is permitted to exit with the items, or the transaction is flagged for audit or further assistance/scrutiny.