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	$111.80	13.534%	$126.931	$126.93	$126.95	$126.90
Purchase #2	$82.29	13.542%	$93.4337	$93.43	$93.45	$93.40
Purchase #3	$65.72	6.135%	$69.7519	$69.75	$69.75	$69.80
Purchase #4	$205.65	8.117%	$222.3426	$222.34	$222.35	$222.30
Purchase #5	$173.47	4.196%	$180.7488	$180.75	$180.75	$180.70
Purchase #6	$99.73	11.341%	$111.0404	$111.04	$111.05	$111.00
Purchase #7	$167.81	4.553%	$175.4504	$175.45	$175.45	$175.50
7 purchase totals =	$906.47		$979.6988	$979.69	$979.75	$979.60