D.C. Code § 37-201.07
No person shall sell, offer for sale, keep, or expose for sale anywhere in the District of Columbia any commodity of any kind as a weight, measure, or numerical count greater than the actual or true weight, measure, or numerical count thereof, and no person shall take or attempt to take more than the actual and true weight, measure, or numerical count of any commodity, when, as buyer, he is permitted by the seller to determine the weight, measure, or numerical count thereof. No person shall charge or collect for any commodity or commodities a sum greater than the price or prices indicated or quoted at the time of sale. No person shall charge, collect, or accept any money for any commodity which he shall not have delivered or which he shall not have agreed to deliver. When a whole number or fraction, or both, are used in representing the price or quantity of any commodity, thing, or service offered or exposed for sale, such number or combination of numbers shall be of such size as to indicate clearly the price or quantity of such commodity, thing or service.
D.C. Code § 37-201.07