California Code, Business and Professions Code - BPC § 13300

(a) The operator of a business establishment that uses a point-of-sale system to sell goods or services to consumers shall ensure that the price of each good or service to be paid by the consumer is conspicuously displayed to the consumer at the time that the price is interpreted by the system.In any instance in which the business advertises a price reduction or discount regarding an item offered for sale, the checkout system customer indicator shall display either the discounted price for that item, or alternatively, the regular price and a credit or reduction of the advertised savings. Any surcharges and the total value to be charged for the overall transaction also shall be displayed for the consumer at least once before the consumer is required to pay for the goods or services. The checkout system customer indicator shall be so positioned, and the prices and amounts displayed shall be of a size and form, as to be easily viewable from a typical and reasonable customer position at each checkout location.

(b) For the purposes of this section, “* * * point-of-sale system” means any computer or electronic system used by a retail establishment such as, but not limited to, Universal Product Code scanners, price lookup codes, or an electronic price lookup system as a means for determining the price of the item being purchased by a consumer.

(c) All point-of-sale systems used by a business establishment on and after January 1, 2007, shall comply with the requirement of subdivision (a).