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	$193.67	10.569%	$214.139	$214.14	$214.15	$214.10
Purchase #2	$95.36	8.566%	$103.5285	$103.53	$103.55	$103.50
Purchase #3	$205.84	5.750%	$217.6758	$217.68	$217.70	$217.70
Purchase #4	$224.72	3.747%	$233.1403	$233.14	$233.15	$233.10
Purchase #5	$111.80	6.452%	$119.0133	$119.01	$119.00	$119.00
Purchase #6	$100.71	11.333%	$112.1235	$112.12	$112.10	$112.10
Purchase #7	$109.55	12.839%	$123.6151	$123.62	$123.60	$123.60
7 purchase totals =	$1,041.65		$1,123.2355	$1,123.24	$1,123.25	$1,123.10