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	$242.55	5.515%	$255.9266	$255.93	$255.95	$255.90
Purchase #2	$15.34	6.105%	$16.2765	$16.28	$16.30	$16.30
Purchase #3	$73.27	10.747%	$81.1443	$81.14	$81.15	$81.10
Purchase #4	$231.99	10.150%	$255.537	$255.54	$255.55	$255.50
Purchase #5	$98.78	12.841%	$111.4643	$111.46	$111.45	$111.50
Purchase #6	$246.40	10.826%	$273.0753	$273.08	$273.10	$273.10
Purchase #7	$45.85	8.127%	$49.5762	$49.58	$49.60	$49.60
7 purchase totals =	$954.18		$1,043.0002	$1,043.01	$1,043.10	$1,043.00