For purposes of the tax imposed by this chapter, if any tangible personal property or any product transferred electronically is taken in trade or in a series of trades as a credit or part payment of a retail sale taxable under this chapter, and the tangible personal property or the product transferred electronically taken in trade is subject to the sales tax imposed by this chapter when sold, the credit or trade-in value allowed by the retailer may not be included as gross receipts.
SDCL 10-45-1.3