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	$164.50	7.322%	$176.5447	$176.54	$176.55	$176.50
Purchase #2	$11.54	7.508%	$12.4064	$12.41	$12.40	$12.40
Purchase #3	$111.43	10.621%	$123.265	$123.27	$123.25	$123.30
Purchase #4	$214.93	13.538%	$244.0272	$244.03	$244.05	$244.00
Purchase #5	$159.65	8.121%	$172.6152	$172.62	$172.60	$172.60
Purchase #6	$64.73	5.858%	$68.5219	$68.52	$68.50	$68.50
Purchase #7	$151.45	5.131%	$159.2209	$159.22	$159.20	$159.20
7 purchase totals =	$878.23		$956.6013	$956.61	$956.55	$956.50