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	$175.43	9.420%	$191.9555	$191.96	$191.95	$192.00
Purchase #2	$69.41	4.555%	$72.5716	$72.57	$72.55	$72.60
Purchase #3	$46.62	12.649%	$52.517	$52.52	$52.50	$52.50
Purchase #4	$121.51	8.650%	$132.0206	$132.02	$132.00	$132.00
Purchase #5	$231.87	5.415%	$244.4258	$244.43	$244.45	$244.40
Purchase #6	$42.30	7.646%	$45.5343	$45.53	$45.55	$45.50
Purchase #7	$32.78	11.577%	$36.5749	$36.57	$36.55	$36.60
7 purchase totals =	$719.92		$775.5997	$775.60	$775.55	$775.60