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	$10.25	13.664%	$11.6506	$11.65	$11.65	$11.70
Purchase #2	$166.98	4.162%	$173.9297	$173.93	$173.95	$173.90
Purchase #3	$217.56	5.390%	$229.2865	$229.29	$229.30	$229.30
Purchase #4	$179.93	5.870%	$190.4919	$190.49	$190.50	$190.50
Purchase #5	$192.26	13.463%	$218.144	$218.14	$218.15	$218.10
Purchase #6	$10.52	11.350%	$11.714	$11.71	$11.70	$11.70
Purchase #7	$168.88	12.723%	$190.3666	$190.37	$190.35	$190.40
7 purchase totals =	$946.38		$1,025.5833	$1,025.58	$1,025.60	$1,025.60