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	$191.62	7.461%	$205.9168	$205.92	$205.90	$205.90
Purchase #2	$10.78	13.837%	$12.2716	$12.27	$12.25	$12.30
Purchase #3	$40.44	11.256%	$44.9919	$44.99	$45.00	$45.00
Purchase #4	$182.51	3.491%	$188.8814	$188.88	$188.90	$188.90
Purchase #5	$156.52	10.157%	$172.4177	$172.42	$172.40	$172.40
Purchase #6	$214.90	7.470%	$230.953	$230.95	$230.95	$231.00
Purchase #7	$154.42	5.287%	$162.5842	$162.58	$162.60	$162.60
7 purchase totals =	$951.19		$1,018.0166	$1,018.01	$1,018.00	$1,018.10