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	$101.27	10.105%	$111.5033	$111.50	$111.50	$111.50
Purchase #2	$76.96	11.198%	$85.578	$85.58	$85.60	$85.60
Purchase #3	$83.53	13.233%	$94.5835	$94.58	$94.60	$94.60
Purchase #4	$170.26	13.735%	$193.6452	$193.65	$193.65	$193.60
Purchase #5	$205.41	6.218%	$218.1824	$218.18	$218.20	$218.20
Purchase #6	$199.43	13.671%	$226.6941	$226.69	$226.70	$226.70
Purchase #7	$79.97	7.287%	$85.7974	$85.80	$85.80	$85.80
7 purchase totals =	$916.83		$1,015.9839	$1,015.98	$1,016.05	$1,016.00