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	$191.85	13.356%	$217.4735	$217.47	$217.45	$217.50
Purchase #2	$190.45	3.403%	$196.931	$196.93	$196.95	$196.90
Purchase #3	$112.51	4.148%	$117.1769	$117.18	$117.20	$117.20
Purchase #4	$95.42	8.619%	$103.6442	$103.64	$103.65	$103.60
Purchase #5	$60.66	12.845%	$68.4518	$68.45	$68.45	$68.50
Purchase #6	$222.54	11.129%	$247.3065	$247.31	$247.30	$247.30
Purchase #7	$99.72	11.869%	$111.5558	$111.56	$111.55	$111.60
7 purchase totals =	$973.15		$1,062.5397	$1,062.54	$1,062.55	$1,062.60