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	$120.58	3.800%	$125.162	$125.16	$125.15	$125.20
Purchase #2	$70.39	12.105%	$78.9107	$78.91	$78.90	$78.90
Purchase #3	$170.92	10.454%	$188.788	$188.79	$188.80	$188.80
Purchase #4	$215.64	13.272%	$244.2597	$244.26	$244.25	$244.30
Purchase #5	$26.25	13.870%	$29.8909	$29.89	$29.90	$29.90
Purchase #6	$213.59	9.348%	$233.5564	$233.56	$233.55	$233.60
Purchase #7	$62.93	5.697%	$66.5151	$66.52	$66.50	$66.50
7 purchase totals =	$880.30		$967.0828	$967.09	$967.05	$967.20