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	$87.37	9.763%	$95.8999	$95.90	$95.90	$95.90
Purchase #2	$202.65	9.865%	$222.6414	$222.64	$222.65	$222.60
Purchase #3	$50.28	8.495%	$54.5513	$54.55	$54.55	$54.60
Purchase #4	$189.99	11.422%	$211.6907	$211.69	$211.70	$211.70
Purchase #5	$245.51	10.427%	$271.1093	$271.11	$271.10	$271.10
Purchase #6	$123.92	8.626%	$134.6093	$134.61	$134.60	$134.60
Purchase #7	$75.61	13.122%	$85.5315	$85.53	$85.55	$85.50
7 purchase totals =	$975.33		$1,076.0334	$1,076.03	$1,076.05	$1,076.00