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	$76.53	7.155%	$82.0057	$82.01	$82.00	$82.00
Purchase #2	$10.32	4.753%	$10.8105	$10.81	$10.80	$10.80
Purchase #3	$246.60	6.434%	$262.4662	$262.47	$262.45	$262.50
Purchase #4	$209.35	10.152%	$230.6032	$230.60	$230.60	$230.60
Purchase #5	$103.51	5.734%	$109.4453	$109.45	$109.45	$109.40
Purchase #6	$218.36	10.669%	$241.6568	$241.66	$241.65	$241.70
Purchase #7	$227.48	4.149%	$236.9181	$236.92	$236.90	$236.90
7 purchase totals =	$1,092.15		$1,173.9058	$1,173.92	$1,173.85	$1,173.90