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	$191.58	4.716%	$200.6149	$200.61	$200.60	$200.60
Purchase #2	$143.66	5.645%	$151.7696	$151.77	$151.75	$151.80
Purchase #3	$165.54	4.407%	$172.8353	$172.84	$172.85	$172.80
Purchase #4	$207.89	10.325%	$229.3546	$229.35	$229.35	$229.40
Purchase #5	$66.89	9.722%	$73.393	$73.39	$73.40	$73.40
Purchase #6	$55.50	4.801%	$58.1646	$58.16	$58.15	$58.20
Purchase #7	$44.66	7.324%	$47.9309	$47.93	$47.95	$47.90
7 purchase totals =	$875.72		$934.0629	$934.05	$934.05	$934.10