The quantities of bottled beer removed subject to tax shall be computed to 5 decimal places in accordance with the table and instructions in § 25.158 . The sum of the quantities computed for any one day will be rounded to 2 decimal places and the tax will be calculated and paid on the rounded sum.
27 C.F.R. § 25.157
Sec. 201, Pub. L. 85-859, 72 Stat. 1333, as amended ( 26 U.S.C. 5051 )