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	$196.30	7.149%	$210.3335	$210.33	$210.35	$210.30
Purchase #2	$77.77	4.279%	$81.0978	$81.10	$81.10	$81.10
Purchase #3	$105.96	5.249%	$111.5218	$111.52	$111.50	$111.50
Purchase #4	$152.78	8.313%	$165.4806	$165.48	$165.50	$165.50
Purchase #5	$133.64	8.693%	$145.2573	$145.26	$145.25	$145.30
Purchase #6	$87.75	4.477%	$91.6786	$91.68	$91.70	$91.70
Purchase #7	$55.37	11.603%	$61.7946	$61.79	$61.80	$61.80
7 purchase totals =	$809.57		$867.1642	$867.16	$867.20	$867.20