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	$202.25	11.133%	$224.7665	$224.77	$224.75	$224.80
Purchase #2	$82.40	11.743%	$92.0762	$92.08	$92.10	$92.10
Purchase #3	$92.75	7.821%	$100.004	$100.00	$100.00	$100.00
Purchase #4	$141.45	9.283%	$154.5808	$154.58	$154.60	$154.60
Purchase #5	$34.35	9.166%	$37.4985	$37.50	$37.50	$37.50
Purchase #6	$111.30	7.375%	$119.5084	$119.51	$119.50	$119.50
Purchase #7	$167.45	3.828%	$173.86	$173.86	$173.85	$173.90
7 purchase totals =	$831.95		$902.2944	$902.30	$902.30	$902.40