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	$83.55	10.666%	$92.4614	$92.46	$92.45	$92.50
Purchase #2	$9.72	8.478%	$10.5441	$10.54	$10.55	$10.50
Purchase #3	$52.87	13.384%	$59.9461	$59.95	$59.95	$59.90
Purchase #4	$240.61	10.810%	$266.6199	$266.62	$266.60	$266.60
Purchase #5	$212.58	4.634%	$222.431	$222.43	$222.45	$222.40
Purchase #6	$224.34	10.395%	$247.6601	$247.66	$247.65	$247.70
Purchase #7	$238.85	7.350%	$256.4055	$256.41	$256.40	$256.40
7 purchase totals =	$1,062.52		$1,156.0681	$1,156.07	$1,156.05	$1,156.00