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	$213.64	11.209%	$237.5869	$237.59	$237.60	$237.60
Purchase #2	$112.82	6.577%	$120.2402	$120.24	$120.25	$120.20
Purchase #3	$150.35	8.302%	$162.8321	$162.83	$162.85	$162.80
Purchase #4	$183.27	3.455%	$189.602	$189.60	$189.60	$189.60
Purchase #5	$13.94	4.141%	$14.5173	$14.52	$14.50	$14.50
Purchase #6	$199.83	10.391%	$220.5943	$220.59	$220.60	$220.60
Purchase #7	$119.68	3.208%	$123.5193	$123.52	$123.50	$123.50
7 purchase totals =	$993.53		$1,068.8921	$1,068.89	$1,068.90	$1,068.80