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	$167.54	9.170%	$182.9034	$182.90	$182.90	$182.90
Purchase #2	$50.92	11.716%	$56.8858	$56.89	$56.90	$56.90
Purchase #3	$145.65	4.126%	$151.6595	$151.66	$151.65	$151.70
Purchase #4	$122.53	6.420%	$130.3964	$130.40	$130.40	$130.40
Purchase #5	$86.80	6.102%	$92.0965	$92.10	$92.10	$92.10
Purchase #6	$222.76	10.620%	$246.4171	$246.42	$246.40	$246.40
Purchase #7	$150.47	3.487%	$155.7169	$155.72	$155.70	$155.70
7 purchase totals =	$946.67		$1,016.0756	$1,016.09	$1,016.05	$1,016.10