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	$149.92	8.213%	$162.2329	$162.23	$162.25	$162.20
Purchase #2	$209.52	13.671%	$238.1635	$238.16	$238.15	$238.20
Purchase #3	$234.78	9.222%	$256.4314	$256.43	$256.45	$256.40
Purchase #4	$161.72	4.733%	$169.3742	$169.37	$169.35	$169.40
Purchase #5	$179.83	6.557%	$191.6215	$191.62	$191.60	$191.60
Purchase #6	$80.56	6.393%	$85.7102	$85.71	$85.70	$85.70
Purchase #7	$87.86	5.848%	$92.9981	$93.00	$93.00	$93.00
7 purchase totals =	$1,104.19		$1,196.5318	$1,196.52	$1,196.50	$1,196.50