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	$219.47	6.246%	$233.1781	$233.18	$233.20	$233.20
Purchase #2	$202.32	6.733%	$215.9422	$215.94	$215.95	$215.90
Purchase #3	$202.85	9.792%	$222.7131	$222.71	$222.70	$222.70
Purchase #4	$72.85	4.339%	$76.011	$76.01	$76.00	$76.00
Purchase #5	$11.49	3.199%	$11.8576	$11.86	$11.85	$11.90
Purchase #6	$76.83	11.641%	$85.7738	$85.77	$85.75	$85.80
Purchase #7	$249.47	3.666%	$258.6156	$258.62	$258.60	$258.60
7 purchase totals =	$1,035.28		$1,104.0914	$1,104.09	$1,104.05	$1,104.10