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	$60.75	11.312%	$67.622	$67.62	$67.60	$67.60
Purchase #2	$69.25	4.766%	$72.5505	$72.55	$72.55	$72.60
Purchase #3	$193.36	10.652%	$213.9567	$213.96	$213.95	$214.00
Purchase #4	$228.63	10.610%	$252.8876	$252.89	$252.90	$252.90
Purchase #5	$40.78	8.280%	$44.1566	$44.16	$44.15	$44.20
Purchase #6	$90.55	10.463%	$100.0242	$100.02	$100.00	$100.00
Purchase #7	$148.56	9.295%	$162.3687	$162.37	$162.35	$162.40
7 purchase totals =	$831.88		$913.5663	$913.57	$913.50	$913.70