Nothing in any law shall in any manner affect the validity of, or render void or voidable, the payment, certification, or acceptance of a check or other negotiable instrument or any other transaction by a bank in this state, because done or performed on any legal holiday or on any Saturday between twelve o'clock (12:00) noon and twelve o'clock (12:00) midnight; provided, that such payment, certification, acceptance, or other transaction would be valid if done or performed on any business day other than a legal holiday, or if done or performed before twelve o'clock (12:00) noon on such Saturday. Nothing herein shall be construed to compel any bank, which by law or custom is entitled to close on a legal holiday, or is entitled to close at twelve o'clock (12:00) noon on any Saturday, to keep open for the transaction of business or to perform any of these acts or transactions on any legal holiday or on any Saturday after twelve o'clock (12:00) noon, except at its own option.