All accounts of the town shall be kept in accordance with the system established by the director of accounts of the Massachusetts Department of Corporations and Taxation, and said accounts shall be audited at such times as he shall determine under the supervision of said director pursuant to the provisions of Chapter 44, Section 35 of the General Laws. Said accounts may be audited by an independent auditor retained by the town at such times and in such manner as the select board may determine in their sole discretion.