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	$116.82	13.453%	$132.5358	$132.54	$132.55	$132.50
Purchase #2	$7.51	11.806%	$8.3966	$8.40	$8.40	$8.40
Purchase #3	$83.90	11.380%	$93.4478	$93.45	$93.45	$93.40
Purchase #4	$70.48	9.573%	$77.2271	$77.23	$77.25	$77.20
Purchase #5	$41.25	10.511%	$45.5858	$45.59	$45.60	$45.60
Purchase #6	$217.75	12.434%	$244.825	$244.83	$244.85	$244.80
Purchase #7	$89.40	11.530%	$99.7078	$99.71	$99.70	$99.70
7 purchase totals =	$627.11		$701.7259	$701.75	$701.80	$701.60