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	$112.48	4.483%	$117.5225	$117.52	$117.50	$117.50
Purchase #2	$78.56	3.727%	$81.4879	$81.49	$81.50	$81.50
Purchase #3	$145.82	12.528%	$164.0883	$164.09	$164.10	$164.10
Purchase #4	$108.79	8.366%	$117.8914	$117.89	$117.90	$117.90
Purchase #5	$184.94	8.540%	$200.7339	$200.73	$200.75	$200.70
Purchase #6	$50.73	13.485%	$57.5709	$57.57	$57.55	$57.60
Purchase #7	$196.66	9.257%	$214.8648	$214.86	$214.85	$214.90
7 purchase totals =	$877.98		$954.1597	$954.15	$954.15	$954.20