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	$105.66	10.667%	$116.9308	$116.93	$116.95	$116.90
Purchase #2	$224.69	4.813%	$235.5043	$235.50	$235.50	$235.50
Purchase #3	$226.83	12.858%	$255.9958	$256.00	$256.00	$256.00
Purchase #4	$234.74	6.262%	$249.4394	$249.44	$249.45	$249.40
Purchase #5	$206.79	7.769%	$222.8555	$222.86	$222.85	$222.90
Purchase #6	$62.35	10.161%	$68.6854	$68.69	$68.70	$68.70
Purchase #7	$41.98	11.268%	$46.7103	$46.71	$46.70	$46.70
7 purchase totals =	$1,103.04		$1,196.1215	$1,196.13	$1,196.15	$1,196.10