All bids must be opened at the time and place specified in the advertised request for bids. Each bid must be accompanied by a certified or cashier’s check of the bidder on a solvent bank, in an amount equal to five percent of the bidder’s bid, to be forfeited to the state highway fund should the bidder fail to effect a contract within ten days after notice of an award or by a bidder’s bond in a sum equal to ten percent of the full amount of the bid, executed by the bidder as principal and by a surety company authorized to do business in this state, conditioned that if the principal’s bid be accepted and the contract awarded to the principal, the principal, within ten days after notice of award, will execute and effect a contract in accordance with the terms of the     principal’s bid and a contractor’s bond as required by law and the regulations and determinations of the department.

All bonds or checks, except those of the responsible bidders submitting the three lowest and best bids, must be returned to the bidders promptly upon opening such bids. The bond or check of the responsible bidder submitting the lowest and best bid may be cashed or retained until the contract has been awarded and executed properly. The bonds or checks of the responsible bidders submitting the second and third lowest and best bids may be returned to the bidders when the department has determined to whom the contract is to be awarded.