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	$55.58	7.863%	$59.9503	$59.95	$59.95	$60.00
Purchase #2	$62.42	8.244%	$67.5659	$67.57	$67.55	$67.60
Purchase #3	$153.55	6.747%	$163.91	$163.91	$163.90	$163.90
Purchase #4	$94.83	4.510%	$99.1068	$99.11	$99.10	$99.10
Purchase #5	$110.96	11.108%	$123.2854	$123.29	$123.30	$123.30
Purchase #6	$116.63	13.566%	$132.452	$132.45	$132.45	$132.50
Purchase #7	$143.42	10.726%	$158.8032	$158.80	$158.80	$158.80
7 purchase totals =	$737.39		$805.0736	$805.08	$805.05	$805.20