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	$184.61	5.603%	$194.9537	$194.95	$194.95	$195.00
Purchase #2	$34.98	12.215%	$39.2528	$39.25	$39.25	$39.30
Purchase #3	$13.98	13.250%	$15.8324	$15.83	$15.85	$15.80
Purchase #4	$90.59	12.363%	$101.7896	$101.79	$101.80	$101.80
Purchase #5	$48.51	4.107%	$50.5023	$50.50	$50.50	$50.50
Purchase #6	$19.79	10.391%	$21.8464	$21.85	$21.85	$21.80
Purchase #7	$177.87	12.853%	$200.7316	$200.73	$200.75	$200.70
7 purchase totals =	$570.33		$624.9088	$624.90	$624.95	$624.90