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	$88.99	7.763%	$95.8983	$95.90	$95.90	$95.90
Purchase #2	$179.70	11.415%	$200.2128	$200.21	$200.20	$200.20
Purchase #3	$18.94	8.173%	$20.488	$20.49	$20.50	$20.50
Purchase #4	$200.61	13.171%	$227.0323	$227.03	$227.05	$227.00
Purchase #5	$214.27	11.438%	$238.7782	$238.78	$238.80	$238.80
Purchase #6	$108.96	11.504%	$121.4948	$121.49	$121.50	$121.50
Purchase #7	$200.66	4.448%	$209.5854	$209.59	$209.60	$209.60
7 purchase totals =	$1,012.13		$1,113.4898	$1,113.49	$1,113.55	$1,113.50