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	$205.92	5.367%	$216.9717	$216.97	$216.95	$217.00
Purchase #2	$74.50	13.557%	$84.6	$84.60	$84.60	$84.60
Purchase #3	$100.95	10.395%	$111.4438	$111.44	$111.45	$111.40
Purchase #4	$112.54	9.798%	$123.5667	$123.57	$123.55	$123.60
Purchase #5	$130.84	6.592%	$139.465	$139.47	$139.45	$139.50
Purchase #6	$241.94	10.783%	$268.0284	$268.03	$268.05	$268.00
Purchase #7	$232.92	8.391%	$252.4643	$252.46	$252.45	$252.50
7 purchase totals =	$1,099.61		$1,196.5399	$1,196.54	$1,196.50	$1,196.60