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	$59.28	13.558%	$67.3172	$67.32	$67.30	$67.30
Purchase #2	$9.89	5.686%	$10.4523	$10.45	$10.45	$10.50
Purchase #3	$65.30	3.551%	$67.6188	$67.62	$67.60	$67.60
Purchase #4	$141.52	5.699%	$149.5852	$149.59	$149.60	$149.60
Purchase #5	$197.67	8.700%	$214.8673	$214.87	$214.85	$214.90
Purchase #6	$231.61	3.772%	$240.3463	$240.35	$240.35	$240.30
Purchase #7	$25.81	7.864%	$27.8397	$27.84	$27.85	$27.80
7 purchase totals =	$731.08		$778.0268	$778.04	$778.00	$778.00