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	$95.48	13.687%	$108.5483	$108.55	$108.55	$108.50
Purchase #2	$57.52	4.265%	$59.9732	$59.97	$59.95	$60.00
Purchase #3	$239.51	5.870%	$253.5692	$253.57	$253.55	$253.60
Purchase #4	$37.48	9.743%	$41.1317	$41.13	$41.15	$41.10
Purchase #5	$72.40	7.153%	$77.5788	$77.58	$77.60	$77.60
Purchase #6	$144.72	7.596%	$155.7129	$155.71	$155.70	$155.70
Purchase #7	$179.78	10.513%	$198.6803	$198.68	$198.70	$198.70
7 purchase totals =	$826.89		$895.1944	$895.19	$895.20	$895.20