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	$117.69	4.105%	$122.5212	$122.52	$122.50	$122.50
Purchase #2	$133.99	5.709%	$141.6395	$141.64	$141.65	$141.60
Purchase #3	$226.29	13.636%	$257.1469	$257.15	$257.15	$257.10
Purchase #4	$86.63	10.463%	$95.6941	$95.69	$95.70	$95.70
Purchase #5	$238.35	7.510%	$256.2501	$256.25	$256.25	$256.30
Purchase #6	$148.55	5.646%	$156.9371	$156.94	$156.95	$156.90
Purchase #7	$41.73	4.110%	$43.4451	$43.45	$43.45	$43.40
7 purchase totals =	$993.23		$1,073.6340	$1,073.64	$1,073.65	$1,073.50