Upon the application of the legislative body or of any holder or other interested party, the Commissioner of Financial Institutions shall examine into the regularity of the issuance of bonds under this division and the sufficiency of the security provided for the payment thereof and if satisfied therewith he or she may certify the same as suitable for investment by savings banks and trustees whereupon the bonds may be used for investment of savings deposits and trust funds. The cost of any such examination may on approval of the legislative body be paid out of any surplus money in the redemption fund not required for the payment of the interest or principal of the bonds.