Mass. Gen. Laws ch. 94 § 295C
A retail dealer of motor fuel shall publicly display and maintain on each pump or other dispensing device from which motor fuel is sold by him, at least 1 sign, clearly visible, stating the price per gallon of each grade of motor fuel sold from the pump or device. A sign shall be not less than 8 inches by 10 inches in size. The price shown on a sign shall include all taxes imposed with respect to the manufacture or sale of the motor fuel sold at that pump or device and shall contain either a statement of the taxes included in the price or, without specifying the amount of the taxes, shall state that such taxes are included in the price. All figures, including fractions, on a sign, other than figures and fractions used in a price computing mechanism and constituting a part of a pump or dispensing device, shall be the same size.
No sign, advertising material or other display or product that is placed upon, above or around a pump or dispenser shall directly or indirectly obscure the posted price sign as required by the preceding paragraph.
Mass. Gen. Laws ch. 94, § 295C