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	$62.62	6.227%	$66.5193	$66.52	$66.50	$66.50
Purchase #2	$222.66	6.726%	$237.6361	$237.64	$237.65	$237.60
Purchase #3	$100.78	3.390%	$104.1964	$104.20	$104.20	$104.20
Purchase #4	$212.65	10.465%	$234.9038	$234.90	$234.90	$234.90
Purchase #5	$205.89	11.660%	$229.8968	$229.90	$229.90	$229.90
Purchase #6	$21.83	4.734%	$22.8634	$22.86	$22.85	$22.90
Purchase #7	$162.27	6.364%	$172.5969	$172.60	$172.60	$172.60
7 purchase totals =	$988.70		$1,068.6127	$1,068.62	$1,068.60	$1,068.60