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	$181.34	10.624%	$200.6056	$200.61	$200.60	$200.60
Purchase #2	$196.95	8.449%	$213.5903	$213.59	$213.60	$213.60
Purchase #3	$67.98	5.325%	$71.5999	$71.60	$71.60	$71.60
Purchase #4	$151.46	6.678%	$161.5745	$161.57	$161.55	$161.60
Purchase #5	$220.59	11.847%	$246.7233	$246.72	$246.70	$246.70
Purchase #6	$24.63	5.275%	$25.9292	$25.93	$25.95	$25.90
Purchase #7	$196.62	9.283%	$214.8722	$214.87	$214.85	$214.90
7 purchase totals =	$1,039.57		$1,134.8950	$1,134.89	$1,134.85	$1,134.90