Tennessee Code Title 45. Banks and Financial Institutions § 45-2-604

(a) A bank shall establish hours of operation it deems necessary or appropriate;  provided, that a bank may not be closed for more than two (2) consecutive calendar days without the prior approval of the commissioner, except a bank, without prior approval, may be closed Saturdays, Sundays, legal holidays and during emergencies as provided in § 45-2-603.

(b) Nothing in any law of this state shall in any manner whatsoever 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 because it was done or performed during any time other than regular banking hours;  provided, that nothing herein shall be construed to compel any bank that by law or custom is entitled to close or suspend business for the whole or any part of any day to keep open for the transaction of business, or to perform any of the acts or transactions aforementioned, on any optional closing day or legal holiday, except at its own option.