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	$144.31	5.117%	$151.6943	$151.69	$151.70	$151.70
Purchase #2	$52.31	11.619%	$58.3879	$58.39	$58.40	$58.40
Purchase #3	$145.88	9.340%	$159.5052	$159.51	$159.50	$159.50
Purchase #4	$128.37	13.116%	$145.207	$145.21	$145.20	$145.20
Purchase #5	$145.82	7.427%	$156.6501	$156.65	$156.65	$156.70
Purchase #6	$169.69	9.435%	$185.7003	$185.70	$185.70	$185.70
Purchase #7	$140.45	6.801%	$150.002	$150.00	$150.00	$150.00
7 purchase totals =	$926.83		$1,007.1468	$1,007.15	$1,007.15	$1,007.20