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	$116.59	10.402%	$128.7177	$128.72	$128.70	$128.70
Purchase #2	$108.48	10.302%	$119.6556	$119.66	$119.65	$119.70
Purchase #3	$104.63	7.272%	$112.2387	$112.24	$112.25	$112.20
Purchase #4	$141.71	11.532%	$158.052	$158.05	$158.05	$158.10
Purchase #5	$120.80	13.412%	$137.0017	$137.00	$137.00	$137.00
Purchase #6	$117.86	4.663%	$123.3558	$123.36	$123.35	$123.40
Purchase #7	$244.83	5.562%	$258.4474	$258.45	$258.45	$258.40
7 purchase totals =	$954.90		$1,037.4689	$1,037.48	$1,037.45	$1,037.50