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	$195.28	9.613%	$214.0523	$214.05	$214.05	$214.10
Purchase #2	$29.59	9.752%	$32.4756	$32.48	$32.50	$32.50
Purchase #3	$167.83	8.432%	$181.9814	$181.98	$182.00	$182.00
Purchase #4	$14.29	8.246%	$15.4684	$15.47	$15.45	$15.50
Purchase #5	$129.51	10.837%	$143.545	$143.55	$143.55	$143.50
Purchase #6	$116.87	9.192%	$127.6127	$127.61	$127.60	$127.60
Purchase #7	$107.48	8.452%	$116.5642	$116.56	$116.55	$116.60
7 purchase totals =	$760.85		$831.6996	$831.70	$831.70	$831.80