That the tax-collector whose appointment is herein provided for shall be vested with the same power and authority in the collection of taxes that sheriffs have, and be subject to the same fines and penalties for failure or neglect of duty. He shall be charged with sums appearing by the tax-lists as due for city taxes. He shall be credited in settlement, as sheriffs are credited, with amounts in suit by appeal, all poll-tax as in personal property certified by the clerk of the commissioners of the county by order of the board of county commissioners to be insolvent and incollectible. He shall at no time retain in his hands over one hundred dollars for a longer time than seven days, under a penalty of two per cent per month to the town upon all sums so unlawfully retained. The board of commissioners, at the meeting before the last regular meeting in each year, shall appoint one or more of their number to be present and assist at the accounting and settlement between the tax-collector and town clerk and audit and settle the accounts of the town clerk. The accounts so audited shall be reported to the board of commissioners, and, when approved by them, shall be recorded in the minute books of said board, and shall be prima facie evidence of their correctness and impeachable only for fraud or specified error. It shall be the duty of said board to remove any tax-collector who shall fail to settle and fully pay up the taxes by law due from him, and he shall not be eligible to re-election to said office: Provided, however, that any male person so certified to be insolvent or delinquent as aforesaid, not previously exempted by order of the board of commissioners, who shall fail to pay said taxes to the collector for six months after such return of insolvents or delinquents as aforesaid, shall be guilty of a misdemeanor, and upon conviction before the mayor shall be fined double the value of the taxes so due, not to exceed in any case fifty dollars; and the mayor, if said person be committed to prison for failure to pay the fine, may employ such offender in working the public streets and public works of said town, as set forth in section fourteen of this act, and said mayor may allow such offender a credit of so much per day on said fine and costs as to him may seem just and reasonable.