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	$177.87	10.670%	$196.8487	$196.85	$196.85	$196.80
Purchase #2	$72.95	10.366%	$80.512	$80.51	$80.50	$80.50
Purchase #3	$227.90	8.197%	$246.581	$246.58	$246.60	$246.60
Purchase #4	$138.31	13.618%	$157.1451	$157.15	$157.15	$157.10
Purchase #5	$29.64	6.837%	$31.6665	$31.67	$31.65	$31.70
Purchase #6	$80.53	12.729%	$90.7807	$90.78	$90.80	$90.80
Purchase #7	$66.52	7.447%	$71.4737	$71.47	$71.45	$71.50
7 purchase totals =	$793.72		$875.0077	$875.01	$875.00	$875.00