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	$102.32	9.147%	$111.6792	$111.68	$111.70	$111.70
Purchase #2	$165.76	5.670%	$175.1586	$175.16	$175.15	$175.20
Purchase #3	$106.41	7.200%	$114.0715	$114.07	$114.05	$114.10
Purchase #4	$78.33	13.545%	$88.9398	$88.94	$88.95	$88.90
Purchase #5	$216.96	11.456%	$241.8149	$241.81	$241.80	$241.80
Purchase #6	$59.56	6.118%	$63.2039	$63.20	$63.20	$63.20
Purchase #7	$214.77	3.190%	$221.6212	$221.62	$221.60	$221.60
7 purchase totals =	$944.11		$1,016.4891	$1,016.48	$1,016.45	$1,016.50