The board of trustees on behalf of the district shall sell its bonds to the best advantage at public sale on sealed bids but for no less than ninety-five cents on the dollar and the proceeds shall be paid over to the treasurer of the district, who shall disburse the proceeds on order of the board of trustees in payment of costs incidental to the holding of the election, the issuance of the bonds and in paying the costs of constructing and carrying into execution the plan of improvement adopted for the district. The sale of the bonds shall be publicly advertised for such time and in such manner as the board directs.