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	$189.72	6.311%	$201.6932	$201.69	$201.70	$201.70
Purchase #2	$69.96	10.714%	$77.4555	$77.46	$77.45	$77.50
Purchase #3	$107.75	3.526%	$111.5493	$111.55	$111.55	$111.50
Purchase #4	$231.28	3.680%	$239.7911	$239.79	$239.80	$239.80
Purchase #5	$208.65	6.689%	$222.6066	$222.61	$222.60	$222.60
Purchase #6	$59.25	3.795%	$61.4985	$61.50	$61.50	$61.50
Purchase #7	$215.78	13.117%	$244.0839	$244.08	$244.10	$244.10
7 purchase totals =	$1,082.39		$1,158.6781	$1,158.68	$1,158.70	$1,158.70