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	$234.42	4.117%	$244.0711	$244.07	$244.05	$244.10
Purchase #2	$125.58	12.331%	$141.0653	$141.07	$141.05	$141.10
Purchase #3	$106.77	8.703%	$116.0622	$116.06	$116.05	$116.10
Purchase #4	$59.47	10.778%	$65.8797	$65.88	$65.90	$65.90
Purchase #5	$37.66	4.404%	$39.3185	$39.32	$39.30	$39.30
Purchase #6	$137.87	7.672%	$148.4474	$148.45	$148.45	$148.40
Purchase #7	$250.26	4.734%	$262.1073	$262.11	$262.10	$262.10
7 purchase totals =	$952.03		$1,016.9515	$1,016.96	$1,016.90	$1,017.00