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	$242.87	8.141%	$262.642	$262.64	$262.65	$262.60
Purchase #2	$99.84	5.431%	$105.2623	$105.26	$105.25	$105.30
Purchase #3	$249.52	10.453%	$275.6023	$275.60	$275.60	$275.60
Purchase #4	$45.83	8.188%	$49.5826	$49.58	$49.60	$49.60
Purchase #5	$115.88	9.493%	$126.8805	$126.88	$126.90	$126.90
Purchase #6	$48.83	9.641%	$53.5377	$53.54	$53.55	$53.50
Purchase #7	$151.36	4.549%	$158.2454	$158.25	$158.25	$158.20
7 purchase totals =	$954.13		$1,031.7528	$1,031.75	$1,031.80	$1,031.70