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	$247.46	8.186%	$267.7171	$267.72	$267.70	$267.70
Purchase #2	$175.63	11.452%	$195.7431	$195.74	$195.75	$195.70
Purchase #3	$182.82	9.344%	$199.9027	$199.90	$199.90	$199.90
Purchase #4	$157.88	6.776%	$168.5779	$168.58	$168.60	$168.60
Purchase #5	$136.80	12.689%	$154.1586	$154.16	$154.15	$154.20
Purchase #6	$130.65	6.513%	$139.1592	$139.16	$139.15	$139.20
Purchase #7	$63.62	12.459%	$71.5464	$71.55	$71.55	$71.50
7 purchase totals =	$1,094.86		$1,196.8050	$1,196.81	$1,196.80	$1,196.80