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	$118.69	7.589%	$127.6974	$127.70	$127.70	$127.70
Purchase #2	$9.72	8.541%	$10.5502	$10.55	$10.55	$10.60
Purchase #3	$185.43	13.358%	$210.1997	$210.20	$210.20	$210.20
Purchase #4	$240.43	7.338%	$258.0728	$258.07	$258.05	$258.10
Purchase #5	$102.70	8.408%	$111.335	$111.34	$111.35	$111.30
Purchase #6	$91.98	13.734%	$104.6125	$104.61	$104.60	$104.60
Purchase #7	$154.55	3.861%	$160.5172	$160.52	$160.50	$160.50
7 purchase totals =	$903.50		$982.9848	$982.99	$982.95	$983.00