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	$215.90	13.257%	$244.5219	$244.52	$244.50	$244.50
Purchase #2	$216.25	11.660%	$241.4648	$241.46	$241.45	$241.50
Purchase #3	$10.84	6.654%	$11.5613	$11.56	$11.55	$11.60
Purchase #4	$136.37	11.274%	$151.7444	$151.74	$151.75	$151.70
Purchase #5	$248.64	3.104%	$256.3578	$256.36	$256.35	$256.40
Purchase #6	$28.51	10.475%	$31.4964	$31.50	$31.50	$31.50
Purchase #7	$199.98	3.381%	$206.7413	$206.74	$206.75	$206.70
7 purchase totals =	$1,056.49		$1,143.8879	$1,143.88	$1,143.85	$1,143.90