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	$111.93	4.483%	$116.9478	$116.95	$116.95	$116.90
Purchase #2	$214.48	4.709%	$224.5799	$224.58	$224.60	$224.60
Purchase #3	$52.75	13.128%	$59.675	$59.68	$59.70	$59.70
Purchase #4	$50.96	13.697%	$57.94	$57.94	$57.95	$57.90
Purchase #5	$180.56	5.867%	$191.1535	$191.15	$191.15	$191.20
Purchase #6	$60.35	10.114%	$66.4538	$66.45	$66.45	$66.50
Purchase #7	$241.50	13.350%	$273.7403	$273.74	$273.75	$273.70
7 purchase totals =	$912.53		$990.4903	$990.49	$990.55	$990.50