In this section the following words have the meanings indicated. “Demand deposit” means a deposit that is payable within 30 days. “Time deposit” means a deposit that is payable after 30 days. “Time deposit” includes a savings account or certificate of deposit that requires at least a 30–day notice before payment. This section does not apply to any deposit of public funds for which the commercial bank pledges collateral. A commercial bank shall have at all times a reserve equal to at least 15 percent of its demand deposits. The board of directors of a commercial bank by resolution shall direct the commercial bank to keep the demand deposit reserve required by this section in: Cash on hand; Demand deposits in a bank of good standing in any state; or As to 5 percent of its demand deposits, on approval of the Commissioner: Registered or coupon bonds; or General obligations of or obligations guaranteed by the United States government, an agency of the United States government, this State, or any political subdivision. A commercial bank shall have at all times a reserve equal to at least 3 percent of its time deposits. The board of directors of a commercial bank by resolution shall direct the commercial bank to keep the time deposit reserves required by this section in: Cash on hand; Deposits in a bank of good standing in any state; or Direct obligations of the United States government or of this State. If the Commissioner determines that a change in the demand deposit reserve or in the time deposit reserve requirements is advisable to maintain sound banking practices or to prevent injurious credit expansion or contraction, the Commissioner may change the requirements as provided in this subsection. Subject to paragraph (3) of this subsection, the Commissioner may adopt rules or regulations to change the requirements as to reserves for commercial banks. The rules and regulations may: Increase the demand deposit reserve to an amount equal to not more than 30 percent of those deposits; Increase the time deposit reserve to an amount equal to not more than 6 percent of those deposits; Decrease the demand deposit reserve to an amount equal to not less than 15 percent of those deposits; Decrease the time deposit reserve to an amount equal to not less than 3 percent of those deposits; and Notwithstanding items (i) through (iv) of this paragraph, increase or decrease the demand deposit reserve or time deposit reserve to conform to the reserve requirements that apply to a member bank of the Federal Reserve System.