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	$94.62	3.515%	$97.9459	$97.95	$97.95	$97.90
Purchase #2	$224.48	12.462%	$252.4547	$252.45	$252.45	$252.50
Purchase #3	$151.82	13.445%	$172.2322	$172.23	$172.25	$172.20
Purchase #4	$145.55	4.103%	$151.5219	$151.52	$151.50	$151.50
Purchase #5	$28.67	13.247%	$32.4679	$32.47	$32.45	$32.50
Purchase #6	$213.82	3.384%	$221.0557	$221.06	$221.05	$221.10
Purchase #7	$244.58	9.696%	$268.2945	$268.29	$268.30	$268.30
7 purchase totals =	$1,103.54		$1,195.9728	$1,195.97	$1,195.95	$1,196.00