S.D. Codified Laws § 5-18B-2
If the invitation for bids is for the construction of a public improvement, each bid shall contain a certified check or a cashier's check, for five percent of the amount of the bid. Such check shall be certified or issued by either a state or a national bank and payable to the purchasing agency or to an officer of the purchasing agency letting the contract and inviting bids. In lieu of a check, a bid may contain a bid bond for ten percent of the amount of the bid. Such bond to be issued by a surety authorized to do business in this state payable to the purchasing agency, as a guaranty that the bidder will enter into a contract with the purchasing agency, its board or officers thereof, in accordance with the terms of the letting and bid in case the bidder be awarded the contract.
SDCL 5-18B-2