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	$216.75	6.247%	$230.2904	$230.29	$230.30	$230.30
Purchase #2	$143.45	3.611%	$148.63	$148.63	$148.65	$148.60
Purchase #3	$184.95	7.852%	$199.4723	$199.47	$199.45	$199.50
Purchase #4	$139.50	3.573%	$144.4843	$144.48	$144.50	$144.50
Purchase #5	$48.85	5.496%	$51.5348	$51.53	$51.55	$51.50
Purchase #6	$147.29	9.136%	$160.7464	$160.75	$160.75	$160.70
Purchase #7	$84.86	6.761%	$90.5974	$90.60	$90.60	$90.60
7 purchase totals =	$965.65		$1,025.7556	$1,025.75	$1,025.80	$1,025.70