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	$172.54	13.604%	$196.0123	$196.01	$196.00	$196.00
Purchase #2	$143.26	13.733%	$162.9339	$162.93	$162.95	$162.90
Purchase #3	$85.29	10.858%	$94.5508	$94.55	$94.55	$94.60
Purchase #4	$231.42	11.476%	$257.9778	$257.98	$258.00	$258.00
Purchase #5	$78.91	10.670%	$87.3297	$87.33	$87.35	$87.30
Purchase #6	$62.77	8.373%	$68.0257	$68.03	$68.05	$68.00
Purchase #7	$203.90	11.663%	$227.6809	$227.68	$227.70	$227.70
7 purchase totals =	$978.09		$1,094.5111	$1,094.51	$1,094.60	$1,094.50