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	$145.77	4.378%	$152.1518	$152.15	$152.15	$152.20
Purchase #2	$195.37	11.319%	$217.4839	$217.48	$217.50	$217.50
Purchase #3	$146.29	3.348%	$151.1878	$151.19	$151.20	$151.20
Purchase #4	$19.43	10.242%	$21.42	$21.42	$21.40	$21.40
Purchase #5	$154.29	13.450%	$175.042	$175.04	$175.05	$175.00
Purchase #6	$103.30	5.118%	$108.5869	$108.59	$108.60	$108.60
Purchase #7	$206.77	8.132%	$223.5845	$223.58	$223.60	$223.60
7 purchase totals =	$971.22		$1,049.4569	$1,049.45	$1,049.50	$1,049.50