S.D. Codified Laws § 10-23-8
Before making a sale of a tax certificate, the treasurer shall offer a tax certificate for each separate parcel of real property for sale in the numerical order in which it appears on the tax list and receive bids for the tax certificate. If any person bids the full amount of the taxes, interest, and costs due, stating in the bid the lowest rate of interest per year at which the bidder will pay the taxes assessed and due against the property, the treasurer shall sell and issue to that bidder the tax certificate. In no case may the rate of interest exceed the rate named in the bid. The bid offered on the tax certificate at the lowest rate of interest per year is considered the best bid. No rate of interest higher than ten percent per year is a valid bid pursuant to this section. Upon redemption of a tax certificate that has been sold or assigned to a purchaser other than the county, a fee shall be deducted from the proceeds paid to the holder of the tax certificate. The county commission may, by resolution, establish a fee not to exceed fifty dollars. No property owner may be assessed this additional fee. The fee shall be deposited in the county general fund.
SDCL 10-23-8