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	$59.41	4.241%	$61.9296	$61.93	$61.95	$61.90
Purchase #2	$140.62	4.307%	$146.6765	$146.68	$146.70	$146.70
Purchase #3	$247.65	12.772%	$279.2799	$279.28	$279.30	$279.30
Purchase #4	$89.38	7.323%	$95.9253	$95.93	$95.95	$95.90
Purchase #5	$161.29	5.342%	$169.9061	$169.91	$169.90	$169.90
Purchase #6	$143.53	8.365%	$155.5363	$155.54	$155.55	$155.50
Purchase #7	$154.74	6.387%	$164.6232	$164.62	$164.60	$164.60
7 purchase totals =	$996.62		$1,073.8769	$1,073.89	$1,073.95	$1,073.80