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	$103.98	7.466%	$111.7431	$111.74	$111.75	$111.70
Purchase #2	$57.73	4.452%	$60.3001	$60.30	$60.30	$60.30
Purchase #3	$87.69	5.468%	$92.4849	$92.48	$92.50	$92.50
Purchase #4	$249.35	10.494%	$275.5168	$275.52	$275.50	$275.50
Purchase #5	$206.90	3.753%	$214.665	$214.67	$214.65	$214.70
Purchase #6	$126.46	7.343%	$135.746	$135.75	$135.75	$135.70
Purchase #7	$198.50	12.785%	$223.8782	$223.88	$223.90	$223.90
7 purchase totals =	$1,030.61		$1,114.3341	$1,114.34	$1,114.35	$1,114.30