Remittance of the full amount of internal revenue tax computed during the return period shall accompany the return, except as prescribed in § 41.115a . Such remittance may be in any form the appropriate TTB officer is authorized to accept under the provisions of § 70.61 of this chapter (Payment by check or money order) and which is acceptable to that officer. In paying the tax, a fractional part of a cent shall be disregarded unless it amounts to one-half cent or more, in which case it shall be increased to one cent.
27 C.F.R. § 41.115
Aug. 16, 1954, Ch. 736, 68A Stat. 778 ( 26 U.S.C. 6313 ) Aug. 16, 1954, ch. 736, 68A Stat. 775 ( 26 U.S.C. 6301 ); June 29, 1956, ch. 462, 70 Stat. 391 ( 26 U.S.C. 6301 )