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	$208.89	12.612%	$235.2352	$235.24	$235.25	$235.20
Purchase #2	$11.82	6.178%	$12.5502	$12.55	$12.55	$12.60
Purchase #3	$85.61	10.852%	$94.9004	$94.90	$94.90	$94.90
Purchase #4	$60.51	8.411%	$65.5995	$65.60	$65.60	$65.60
Purchase #5	$89.91	13.447%	$102.0002	$102.00	$102.00	$102.00
Purchase #6	$151.91	5.671%	$160.5248	$160.52	$160.50	$160.50
Purchase #7	$51.96	4.759%	$54.4328	$54.43	$54.45	$54.40
7 purchase totals =	$660.61		$725.2431	$725.24	$725.25	$725.20