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	$159.78	4.495%	$166.9621	$166.96	$166.95	$167.00
Purchase #2	$205.29	6.761%	$219.1697	$219.17	$219.15	$219.20
Purchase #3	$63.83	12.237%	$71.6409	$71.64	$71.65	$71.60
Purchase #4	$58.31	4.869%	$61.1491	$61.15	$61.15	$61.10
Purchase #5	$233.42	3.459%	$241.494	$241.49	$241.50	$241.50
Purchase #6	$37.58	11.278%	$41.8183	$41.82	$41.80	$41.80
Purchase #7	$232.28	6.411%	$247.1715	$247.17	$247.15	$247.20
7 purchase totals =	$990.49		$1,049.4056	$1,049.40	$1,049.35	$1,049.40