S.D. Codified Laws § 37-10-16
Any retailer may advertise, offer to sell, or sell cigarettes at a price made in good faith to meet the price of a competitor who is selling the same article in this state at cost to him as a retailer as prescribed in this chapter. Any wholesaler may advertise, offer to sell, or sell cigarettes at a price made in good faith to meet the price of a competitor who is rendering the same type of service and is selling the same article at cost to him as a wholesaler as prescribed in this chapter. The price of cigarettes advertised, offered for sale, or sold under the exceptions specified in §§ 37-10-18 to 37-10-22, inclusive, shall not be considered the price of a competitor and shall not be used as a basis for establishing prices below cost, nor shall the price established at a bankruptcy sale be considered the price of a competitor within the meaning of this section.
SDCL 37-10-16