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	$86.41	10.183%	$95.2091	$95.21	$95.20	$95.20
Purchase #2	$12.72	8.561%	$13.809	$13.81	$13.80	$13.80
Purchase #3	$123.55	6.231%	$131.2484	$131.25	$131.25	$131.20
Purchase #4	$101.37	11.646%	$113.1756	$113.18	$113.20	$113.20
Purchase #5	$200.27	13.456%	$227.2183	$227.22	$227.20	$227.20
Purchase #6	$187.85	6.717%	$200.4679	$200.47	$200.45	$200.50
Purchase #7	$150.25	13.836%	$171.0386	$171.04	$171.05	$171.00
7 purchase totals =	$862.42		$952.1669	$952.18	$952.15	$952.10