No stamps evidencing payment of the tax prescribed in § 10-50-3 shall be in a denomination of less than one cent and whenever the tax at the rate therein prescribed shall be a specified amount plus a fractional part of one cent, the package or carton shall be stamped for the next full cent, provided, that whenever the tax at the rate therein prescribed shall amount to twelve cents the package or carton shall be stamped for the exact amount of twelve cents.
SDCL 10-50-5