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	$192.82	11.428%	$214.8555	$214.86	$214.85	$214.90
Purchase #2	$243.53	5.303%	$256.4444	$256.44	$256.45	$256.40
Purchase #3	$152.49	4.437%	$159.256	$159.26	$159.25	$159.30
Purchase #4	$45.82	8.535%	$49.7307	$49.73	$49.75	$49.70
Purchase #5	$104.93	6.642%	$111.8995	$111.90	$111.90	$111.90
Purchase #6	$184.87	3.563%	$191.4569	$191.46	$191.45	$191.50
Purchase #7	$81.37	6.261%	$86.4646	$86.46	$86.45	$86.50
7 purchase totals =	$1,005.83		$1,070.1076	$1,070.11	$1,070.10	$1,070.20