Any retailer making sales of tangible personal property to purchasers in this state by mail, telephone, the internet, or other media which has a contractual relationship with an entity to provide and perform installation, maintenance, or repair services for the retailer's purchasers within this state shall be included within the definition of retailer under the provisions of §§ 10-45-2.5 to 10-45-2.9, inclusive.
SDCL 10-45-2.9