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	$204.25	6.281%	$217.0789	$217.08	$217.10	$217.10
Purchase #2	$38.53	5.116%	$40.5012	$40.50	$40.50	$40.50
Purchase #3	$46.81	3.671%	$48.5284	$48.53	$48.55	$48.50
Purchase #4	$85.57	11.580%	$95.479	$95.48	$95.50	$95.50
Purchase #5	$216.39	5.225%	$227.6964	$227.70	$227.70	$227.70
Purchase #6	$155.41	3.142%	$160.293	$160.29	$160.30	$160.30
Purchase #7	$212.77	13.703%	$241.9259	$241.93	$241.95	$241.90
7 purchase totals =	$959.73		$1,031.5028	$1,031.51	$1,031.60	$1,031.50