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	$213.60	13.160%	$241.7098	$241.71	$241.70	$241.70
Purchase #2	$230.55	5.145%	$242.4118	$242.41	$242.40	$242.40
Purchase #3	$59.58	6.215%	$63.2829	$63.28	$63.30	$63.30
Purchase #4	$11.44	4.240%	$11.9251	$11.93	$11.95	$11.90
Purchase #5	$112.45	10.249%	$123.975	$123.98	$124.00	$124.00
Purchase #6	$138.37	12.541%	$155.723	$155.72	$155.70	$155.70
Purchase #7	$166.73	7.293%	$178.8896	$178.89	$178.90	$178.90
7 purchase totals =	$932.72		$1,017.9172	$1,017.92	$1,017.95	$1,017.90