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	$141.48	6.775%	$151.0653	$151.07	$151.05	$151.10
Purchase #2	$140.90	6.422%	$149.9486	$149.95	$149.95	$149.90
Purchase #3	$236.72	11.196%	$263.2232	$263.22	$263.20	$263.20
Purchase #4	$65.89	9.471%	$72.1304	$72.13	$72.15	$72.10
Purchase #5	$121.91	4.109%	$126.9193	$126.92	$126.90	$126.90
Purchase #6	$151.64	11.231%	$168.6707	$168.67	$168.65	$168.70
Purchase #7	$190.68	4.105%	$198.5074	$198.51	$198.50	$198.50
7 purchase totals =	$1,049.22		$1,130.4649	$1,130.47	$1,130.40	$1,130.40