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	$221.41	10.868%	$245.4728	$245.47	$245.45	$245.50
Purchase #2	$130.53	11.832%	$145.9743	$145.97	$145.95	$146.00
Purchase #3	$99.97	5.643%	$105.6113	$105.61	$105.60	$105.60
Purchase #4	$219.31	11.300%	$244.092	$244.09	$244.10	$244.10
Purchase #5	$217.26	9.754%	$238.4515	$238.45	$238.45	$238.50
Purchase #6	$26.92	9.235%	$29.4061	$29.41	$29.40	$29.40
Purchase #7	$102.66	11.458%	$114.4228	$114.42	$114.40	$114.40
7 purchase totals =	$1,018.06		$1,123.4308	$1,123.42	$1,123.35	$1,123.50