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	$87.82	12.245%	$98.5736	$98.57	$98.55	$98.60
Purchase #2	$75.35	8.627%	$81.8504	$81.85	$81.85	$81.90
Purchase #3	$11.95	3.499%	$12.3681	$12.37	$12.35	$12.40
Purchase #4	$40.46	5.650%	$42.746	$42.75	$42.75	$42.70
Purchase #5	$162.28	6.366%	$172.6107	$172.61	$172.60	$172.60
Purchase #6	$246.78	13.254%	$279.4882	$279.49	$279.50	$279.50
Purchase #7	$246.75	5.523%	$260.378	$260.38	$260.40	$260.40
7 purchase totals =	$871.39		$948.0150	$948.02	$948.00	$948.10