California Code, Business and Professions Code - BPC § 13470

(a) A person shall not sell at retail to the general public, any motor vehicle fuel from any place of business in this state unless there is displayed on the dispensing apparatus in a conspicuous place at least one sign or price indicator showing the total price per gallon, liter, or other unit of measurement adopted pursuant to Section 12107, 13404, or 13404.5 of all motor vehicle fuel sold therefrom.  The total price per gallon, liter, or other unit of measurement shall include applicable fuel taxes and all sales taxes.

(c) When a discount is offered from a dispenser computing only at a higher price, at least one sign or label shall be conspicuously displayed on the dispenser indicating that the dispenser is computing at the higher price and indicating the amount of the discount per unit of measurement in letters and numerals not less than one-half inch high.

(d) If motor vehicle fuel is sold by unit of measurement other than gallon, that unit shall be conspicuously displayed on the side of the dispensing apparatus from which service can be made.