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	$191.84	4.554%	$200.5764	$200.58	$200.60	$200.60
Purchase #2	$93.31	7.738%	$100.5303	$100.53	$100.55	$100.50
Purchase #3	$120.30	11.672%	$134.3414	$134.34	$134.35	$134.30
Purchase #4	$151.99	4.160%	$158.3128	$158.31	$158.30	$158.30
Purchase #5	$185.87	10.850%	$206.0369	$206.04	$206.05	$206.00
Purchase #6	$167.55	3.493%	$173.4025	$173.40	$173.40	$173.40
Purchase #7	$64.57	9.181%	$70.4982	$70.50	$70.50	$70.50
7 purchase totals =	$975.43		$1,043.6985	$1,043.70	$1,043.75	$1,043.60