When in his or her discretion local conditions so warrant, the treasurer may waive security for the portion of any deposits as is insured pursuant to federal law, notwithstanding this article. For deposits equivalent to and not less than the maximum amount insured pursuant to federal law for which a treasurer has waived security under this section, a treasurer at his or her discretion may also waive security for the interest accrued on the deposits which, when added to the deposits, would cause the sum of the interest and deposits to exceed the maximum amount insured pursuant to federal law, provided that the interest is computed by the depository on the

average daily balance of the deposits, paid monthly and computed on a 360-day basis.