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	$218.70	10.527%	$241.7225	$241.72	$241.70	$241.70
Purchase #2	$64.90	7.105%	$69.5111	$69.51	$69.50	$69.50
Purchase #3	$85.98	12.823%	$97.0052	$97.01	$97.00	$97.00
Purchase #4	$208.89	9.558%	$228.8557	$228.86	$228.85	$228.90
Purchase #5	$209.90	4.406%	$219.1482	$219.15	$219.15	$219.10
Purchase #6	$54.75	9.169%	$59.77	$59.77	$59.75	$59.80
Purchase #7	$25.55	7.722%	$27.523	$27.52	$27.50	$27.50
7 purchase totals =	$868.67		$943.5357	$943.54	$943.45	$943.50