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	$217.95	3.296%	$225.1336	$225.13	$225.15	$225.10
Purchase #2	$107.59	4.521%	$112.4541	$112.45	$112.45	$112.50
Purchase #3	$148.42	3.644%	$153.8284	$153.83	$153.85	$153.80
Purchase #4	$139.41	5.169%	$146.6161	$146.62	$146.60	$146.60
Purchase #5	$36.79	4.409%	$38.4121	$38.41	$38.40	$38.40
Purchase #6	$148.67	12.488%	$167.2359	$167.24	$167.25	$167.20
Purchase #7	$175.31	8.579%	$190.3498	$190.35	$190.35	$190.30
7 purchase totals =	$974.14		$1,034.0300	$1,034.03	$1,034.05	$1,033.90