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	$117.28	5.425%	$123.6424	$123.64	$123.65	$123.60
Purchase #2	$9.87	7.432%	$10.6035	$10.60	$10.60	$10.60
Purchase #3	$197.36	12.655%	$222.3359	$222.34	$222.35	$222.30
Purchase #4	$22.27	12.689%	$25.0958	$25.10	$25.10	$25.10
Purchase #5	$233.43	5.186%	$245.5357	$245.54	$245.55	$245.50
Purchase #6	$32.67	11.363%	$36.3823	$36.38	$36.40	$36.40
Purchase #7	$139.32	8.574%	$151.2653	$151.27	$151.25	$151.30
7 purchase totals =	$752.20		$814.8609	$814.87	$814.90	$814.80