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	$59.46	3.446%	$61.509	$61.51	$61.50	$61.50
Purchase #2	$64.91	7.108%	$69.5238	$69.52	$69.50	$69.50
Purchase #3	$116.87	3.178%	$120.5841	$120.58	$120.60	$120.60
Purchase #4	$139.38	4.548%	$145.719	$145.72	$145.70	$145.70
Purchase #5	$105.96	8.409%	$114.8702	$114.87	$114.85	$114.90
Purchase #6	$95.70	3.578%	$99.1241	$99.12	$99.10	$99.10
Purchase #7	$243.77	4.536%	$254.8274	$254.83	$254.85	$254.80
7 purchase totals =	$826.05		$866.1576	$866.15	$866.10	$866.10