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	$208.53	3.383%	$215.5846	$215.58	$215.60	$215.60
Purchase #2	$6.81	4.672%	$7.1282	$7.13	$7.15	$7.10
Purchase #3	$52.88	8.274%	$57.2553	$57.26	$57.25	$57.30
Purchase #4	$100.59	7.628%	$108.263	$108.26	$108.25	$108.30
Purchase #5	$7.52	4.418%	$7.8522	$7.85	$7.85	$7.90
Purchase #6	$45.80	5.738%	$48.428	$48.43	$48.45	$48.40
Purchase #7	$40.65	6.821%	$43.4227	$43.42	$43.40	$43.40
7 purchase totals =	$462.78		$487.9340	$487.93	$487.95	$488.00