Let's do some math ..  Rounding examples of 7 random hypothetical purchases:
Case	Tag   Price	Sales   Tax %	Raw Total   Incl. Sales Tax	Rounded   to Penny	Rounded   to Nickel	Rounded   to Dime
Purchase #1	$31.86	13.745%	$36.2392	$36.24	$36.25	$36.20
Purchase #2	$244.25	12.232%	$274.1267	$274.13	$274.15	$274.10
Purchase #3	$114.29	11.201%	$127.0916	$127.09	$127.10	$127.10
Purchase #4	$103.92	12.475%	$116.884	$116.88	$116.90	$116.90
Purchase #5	$207.78	12.774%	$234.3218	$234.32	$234.30	$234.30
Purchase #6	$60.39	11.609%	$67.4007	$67.40	$67.40	$67.40
Purchase #7	$213.47	12.148%	$239.4023	$239.40	$239.40	$239.40
7 purchase totals =	$975.96		$1,095.4663	$1,095.46	$1,095.50	$1,095.40