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	$171.43	13.436%	$194.4633	$194.46	$194.45	$194.50
Purchase #2	$203.26	9.143%	$221.8441	$221.84	$221.85	$221.80
Purchase #3	$169.77	9.477%	$185.8591	$185.86	$185.85	$185.90
Purchase #4	$216.84	3.521%	$224.4749	$224.47	$224.45	$224.50
Purchase #5	$28.93	4.837%	$30.3293	$30.33	$30.35	$30.30
Purchase #6	$26.67	10.743%	$29.5352	$29.54	$29.55	$29.50
Purchase #7	$108.29	7.485%	$116.3955	$116.40	$116.40	$116.40
7 purchase totals =	$925.19		$1,002.9014	$1,002.90	$1,002.90	$1,002.90