No commodity shall be so wrapped or labeled, nor shall it be in a container so made, formed, or filled as to mislead the purchaser as to the quantity of the contents of the commodity in the package, and the contents of a container shall not fall below such reasonable standard of fill as has been prescribed for the commodity by rule of the board.

For commodities measured by volume and packaged in containers standardized as to capacity or generally recognized by consumers as having a set capacity, the standard of fill shall be equal to that capacity, e.g., the volume of fill in the commonly designed one-gallon jug shall be one gallon.