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	$195.50	11.469%	$217.9219	$217.92	$217.90	$217.90
Purchase #2	$40.56	8.173%	$43.875	$43.88	$43.90	$43.90
Purchase #3	$99.71	8.130%	$107.8164	$107.82	$107.80	$107.80
Purchase #4	$247.57	9.516%	$271.1288	$271.13	$271.15	$271.10
Purchase #5	$77.29	11.203%	$85.9488	$85.95	$85.95	$85.90
Purchase #6	$92.89	9.535%	$101.7471	$101.75	$101.75	$101.70
Purchase #7	$239.46	7.114%	$256.4952	$256.50	$256.50	$256.50
7 purchase totals =	$992.98		$1,084.9332	$1,084.95	$1,084.95	$1,084.80