SDCL § 10-23-24: Bidding off on behalf of county as purchaser at tax sale.

If there are no other bidders offering the amount due under a tax certificate sale, the treasurer may bid off all or any tax certificate offered at the sale for the amount of taxes, penalty, interest, and costs due and unpaid on the property, in the name of the county. The county may acquire all the rights, both legal and equitable, that any purchaser may acquire by reason of the purchase.