Section 35. Every town treasurer shall give bond annually for the faithful performance of his duties in a form approved by the commissioner of revenue and in such sum, not less than the amount established by said commissioner, as shall be fixed by the selectmen or the mayor and aldermen, and if he fails to give such bond within ten days after his election or appointment, or if within ten days after the expiration of said bond or any renewal of said bond he fails to file a renewal thereof, the selectmen or the mayor and aldermen shall declare the office vacant and the vacancy shall be filled in the manner prescribed by section forty or sixty-one A, as the case may be. He shall receive and take charge of all money belonging to the town, and pay over and account for the same according to the order of the town or of its authorized officers. No other person shall pay any bill of any department; provided, however, this provision shall not prohibit the treasurer from paying such bill by the use of bank treasurer's or cashier's check. He shall have the authority given to an auditor by section fifty-one, and shall annually render a true account of all his receipts and disbursements and a report of his official acts. The bond required herein shall cover the duties of the treasurer with respect to trust funds and funds of retirement systems which are in his custody by virtue of his office, and any such funds, for the purposes of said bond, shall be deemed to be public funds.