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	$91.38	4.612%	$95.5944	$95.59	$95.60	$95.60
Purchase #2	$116.52	13.760%	$132.5532	$132.55	$132.55	$132.60
Purchase #3	$217.71	3.758%	$225.8915	$225.89	$225.90	$225.90
Purchase #4	$63.75	10.620%	$70.5203	$70.52	$70.50	$70.50
Purchase #5	$154.90	12.258%	$173.8876	$173.89	$173.90	$173.90
Purchase #6	$137.48	8.723%	$149.4724	$149.47	$149.45	$149.50
Purchase #7	$200.48	10.191%	$220.9109	$220.91	$220.90	$220.90
7 purchase totals =	$982.22		$1,068.8303	$1,068.82	$1,068.80	$1,068.90