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	$147.62	11.737%	$164.9462	$164.95	$164.95	$164.90
Purchase #2	$151.35	11.733%	$169.1079	$169.11	$169.10	$169.10
Purchase #3	$18.46	13.211%	$20.8988	$20.90	$20.90	$20.90
Purchase #4	$97.72	7.448%	$104.9982	$105.00	$105.00	$105.00
Purchase #5	$94.37	11.833%	$105.5368	$105.54	$105.55	$105.50
Purchase #6	$175.33	4.165%	$182.6325	$182.63	$182.65	$182.60
Purchase #7	$48.76	8.308%	$52.811	$52.81	$52.80	$52.80
7 purchase totals =	$733.61		$800.9314	$800.94	$800.95	$800.80