California law says that electronic sales systems such as barcode-based cash registers must be set up in a way that allows a customer ample opportunity to see the price that is being charged for each item before making payment. Violating this law can lead to a civil financial penalty.
A point of sale system is legally defined in California as "any computer or electronic system used by a retail establishment." The principle is that such systems allow store staff to automatically retrieve the listed price of an item rather than manually type it in from the price label. Such systems commonly involve barcodes and have the added function of tracking stock levels on store shelves.
The California Business and Professions Code covers the consumer's rights at the point the sale is "rung up" on the point of sale system. Under the law, the consumer must be able to see clear details of the price being charged for each item, along with any surcharges and discounts. This will usually take the form of an electronic screen readily visible to the customer while the items are rung up. The principle of the law is to give the customer a fair opportunity to spot any disparities between the price listed on display and the price being rung up before paying for the transaction.
Breaching this law is a civil rather than criminal offense. The maximum penalty is $1,000 for each violation. Offenders must be given written notice of a proposed penalty and have 20 days to demand a hearing on the case. Such a hearing may lead to the penalty being set aside, reduced or increased.
Contrary to popular misconception, a store is not obliged to sell goods at the price displayed on store labels, whether this price was listed intentionally or mistakenly. This is because contract law means that price displays do not form a contractual offer but rather an "invitation to bargain." That is to say, they provide information, but technically the customer makes the offer to purchase at this price and the store has the right to reject this offer.