The Board of Estimates, at appropriate intervals, shall engage an independent firm of certified public accountants to audit:the financial transactions of the Department of Audits; and the comprehensive annual financial report of the City. The Board of Estimates may engage an independent firm of certified public accountants to audit the financial transactions of any municipal agency and to examine the fiscal procedures, records, accounts, and methods of any municipal agency, including the Department of Audits. The independent firm of certified public accountants shall make reports of its audits, examinations, and recommendations to the Board of Estimates.