For the purpose of making partial payments as the work progresses under the provisions of sections 17-970 to 17-976, warrants may be issued by the governing body upon certificates of the engineer in charge showing the amount of work completed and materials necessarily purchased and delivered for the orderly and proper continuation of the project in the total amount of not to exceed ninety-five percent of the cost thereof. Upon the completion and acceptance of the work a final warrant shall be issued for the balance of the amount due the contractor or other party entitled to payment. The governing body shall pay to the contractor interest at the rate of eight percent per annum on the amounts due on partial and final payments beginning forty-five days after the certification of the amounts due by the engineer in charge and approval by the governing body, and running until the date that the warrant is tendered to the contractor. Such warrants shall be payable in the order of their number and shall bear interest at not to exceed six percent per annum from the date of registration until paid.