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	$66.92	10.660%	$74.0537	$74.05	$74.05	$74.10
Purchase #2	$230.58	4.867%	$241.8023	$241.80	$241.80	$241.80
Purchase #3	$223.63	9.402%	$244.6557	$244.66	$244.65	$244.70
Purchase #4	$50.63	4.694%	$53.0066	$53.01	$53.00	$53.00
Purchase #5	$121.91	4.354%	$127.218	$127.22	$127.20	$127.20
Purchase #6	$103.72	7.756%	$111.7645	$111.76	$111.75	$111.80
Purchase #7	$145.27	10.161%	$160.0309	$160.03	$160.05	$160.00
7 purchase totals =	$942.66		$1,012.5317	$1,012.53	$1,012.50	$1,012.60