A fine not exceeding $20.00 and costs of prosecution may be imposed for the breach of any by-law, rule, or ordinance, or of any section of this act unless some other sum is named in the section. In case such fine and costs are not paid, the alternative sentence shall be confinement in the house of correction as is provided by law in other criminal cases. Prosecution for offenses under this act, unless otherwise specified, shall be commenced within three months after the commission of the offense. All fines shall be paid to the Town Treasurer and justices shall have jurisdiction where punishment is by fine not exceeding $20.00.