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	$181.54	8.212%	$196.4481	$196.45	$196.45	$196.40
Purchase #2	$234.79	9.388%	$256.8321	$256.83	$256.85	$256.80
Purchase #3	$132.35	7.248%	$141.9427	$141.94	$141.95	$141.90
Purchase #4	$92.98	10.531%	$102.7717	$102.77	$102.75	$102.80
Purchase #5	$146.32	8.105%	$158.1792	$158.18	$158.20	$158.20
Purchase #6	$167.43	4.297%	$174.6245	$174.62	$174.60	$174.60
Purchase #7	$20.41	13.420%	$23.149	$23.15	$23.15	$23.10
7 purchase totals =	$975.82		$1,053.9473	$1,053.94	$1,053.95	$1,053.80