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	$175.72	10.836%	$194.761	$194.76	$194.75	$194.80
Purchase #2	$149.25	11.671%	$166.669	$166.67	$166.65	$166.70
Purchase #3	$152.77	13.165%	$172.8822	$172.88	$172.90	$172.90
Purchase #4	$209.83	8.722%	$228.1314	$228.13	$228.15	$228.10
Purchase #5	$37.88	9.378%	$41.4324	$41.43	$41.45	$41.40
Purchase #6	$83.46	9.217%	$91.1525	$91.15	$91.15	$91.20
Purchase #7	$129.41	13.628%	$147.046	$147.05	$147.05	$147.00
7 purchase totals =	$938.32		$1,042.0745	$1,042.07	$1,042.10	$1,042.10