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	$207.57	8.245%	$224.6841	$224.68	$224.70	$224.70
Purchase #2	$204.59	6.507%	$217.9027	$217.90	$217.90	$217.90
Purchase #3	$78.45	4.871%	$82.2713	$82.27	$82.25	$82.30
Purchase #4	$76.48	8.294%	$82.8233	$82.82	$82.80	$82.80
Purchase #5	$208.90	3.633%	$216.4893	$216.49	$216.50	$216.50
Purchase #6	$80.65	12.211%	$90.4982	$90.50	$90.50	$90.50
Purchase #7	$13.79	5.277%	$14.5177	$14.52	$14.50	$14.50
7 purchase totals =	$870.43		$929.1866	$929.18	$929.15	$929.20