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	$44.66	9.152%	$48.7473	$48.75	$48.75	$48.70
Purchase #2	$177.68	10.486%	$196.3115	$196.31	$196.30	$196.30
Purchase #3	$34.67	13.612%	$39.3893	$39.39	$39.40	$39.40
Purchase #4	$244.50	10.671%	$270.5906	$270.59	$270.60	$270.60
Purchase #5	$210.67	12.498%	$236.9995	$237.00	$237.00	$237.00
Purchase #6	$164.57	7.247%	$176.4964	$176.50	$176.50	$176.50
Purchase #7	$104.69	11.308%	$116.5283	$116.53	$116.55	$116.50
7 purchase totals =	$981.44		$1,085.0629	$1,085.07	$1,085.10	$1,085.00