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	$92.63	13.854%	$105.463	$105.46	$105.45	$105.50
Purchase #2	$9.51	8.285%	$10.2979	$10.30	$10.30	$10.30
Purchase #3	$82.60	4.196%	$86.0659	$86.07	$86.05	$86.10
Purchase #4	$19.80	12.554%	$22.2857	$22.29	$22.30	$22.30
Purchase #5	$44.41	5.384%	$46.801	$46.80	$46.80	$46.80
Purchase #6	$53.62	4.455%	$56.0088	$56.01	$56.00	$56.00
Purchase #7	$141.59	6.766%	$151.17	$151.17	$151.15	$151.20
7 purchase totals =	$444.16		$478.0923	$478.10	$478.05	$478.20