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	$59.86	4.253%	$62.4058	$62.41	$62.40	$62.40
Purchase #2	$143.45	5.792%	$151.7586	$151.76	$151.75	$151.80
Purchase #3	$23.39	6.718%	$24.9613	$24.96	$24.95	$25.00
Purchase #4	$140.45	8.584%	$152.5062	$152.51	$152.50	$152.50
Purchase #5	$171.41	4.771%	$179.588	$179.59	$179.60	$179.60
Purchase #6	$236.56	8.302%	$256.1992	$256.20	$256.20	$256.20
Purchase #7	$124.35	13.795%	$141.5041	$141.50	$141.50	$141.50
7 purchase totals =	$899.47		$968.9232	$968.93	$968.90	$969.00