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	$194.54	8.601%	$211.2724	$211.27	$211.25	$211.30
Purchase #2	$58.41	5.142%	$61.4134	$61.41	$61.40	$61.40
Purchase #3	$85.77	10.414%	$94.7021	$94.70	$94.70	$94.70
Purchase #4	$31.82	4.143%	$33.1383	$33.14	$33.15	$33.10
Purchase #5	$21.52	3.614%	$22.2977	$22.30	$22.30	$22.30
Purchase #6	$61.27	7.140%	$65.6447	$65.64	$65.65	$65.60
Purchase #7	$222.44	3.338%	$229.865	$229.87	$229.85	$229.90
7 purchase totals =	$675.77		$718.3336	$718.33	$718.30	$718.30