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	$125.27	3.345%	$129.4603	$129.46	$129.45	$129.50
Purchase #2	$223.46	12.314%	$250.9769	$250.98	$251.00	$251.00
Purchase #3	$37.37	8.401%	$40.5095	$40.51	$40.50	$40.50
Purchase #4	$55.41	10.700%	$61.3389	$61.34	$61.35	$61.30
Purchase #5	$227.34	3.352%	$234.9604	$234.96	$234.95	$235.00
Purchase #6	$157.81	3.162%	$162.8	$162.80	$162.80	$162.80
Purchase #7	$241.43	12.602%	$271.855	$271.86	$271.85	$271.90
7 purchase totals =	$1,068.09		$1,151.9010	$1,151.91	$1,151.90	$1,152.00