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	$214.66	9.716%	$235.5164	$235.52	$235.50	$235.50
Purchase #2	$215.76	8.371%	$233.8213	$233.82	$233.80	$233.80
Purchase #3	$79.59	3.646%	$82.4919	$82.49	$82.50	$82.50
Purchase #4	$246.82	3.748%	$256.0708	$256.07	$256.05	$256.10
Purchase #5	$11.35	5.275%	$11.9487	$11.95	$11.95	$11.90
Purchase #6	$105.29	10.180%	$116.0085	$116.01	$116.00	$116.00
Purchase #7	$80.47	5.762%	$85.1067	$85.11	$85.10	$85.10
7 purchase totals =	$953.94		$1,020.9643	$1,020.97	$1,020.90	$1,020.90