No person who holds a biennial license to sell alcoholic liquors for on-premises consumption may advertise, sell, or dispense these beverages for free, at a price less than one-half of the price regularly charged, or on a two or more for the price of one basis. Alcoholic liquors may be sold at a price less than the price regularly charged from four o’clock p.m. until eight o’clock p.m. only. The prohibition against dispensing the beverages for free does not apply to dispensing to a customer on an individual basis, to a fraternal organization in the course of its fund-raising activities, to a person attending a private function on premises for which a biennial license has been issued, or to a customer attending a function sponsored by the person who holds a biennial license. However, no more than two functions may be sponsored each year, and must be authorized by the department. A person who violates this section is guilty of a misdemeanor and, upon conviction, must be fined not less than one hundred dollars or imprisoned not less than three months, in the discretion of the court.