350.42.7. If a beverage in a filled and sealed returnable container in respect of which there is a returnable container charge is held at any time by a person for consumption, use or supply in the course of commercial activities of the person, the fair market value of the beverage at that time is deemed not to include the amount that would be determined as the refund for the container if the beverage were supplied by the person at that time in a filled and sealed container.