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	$187.98	11.115%	$208.874	$208.87	$208.85	$208.90
Purchase #2	$140.62	10.730%	$155.7085	$155.71	$155.70	$155.70
Purchase #3	$149.83	5.779%	$158.4887	$158.49	$158.50	$158.50
Purchase #4	$250.99	11.323%	$279.4096	$279.41	$279.40	$279.40
Purchase #5	$76.82	8.840%	$83.6109	$83.61	$83.60	$83.60
Purchase #6	$59.45	10.630%	$65.7695	$65.77	$65.75	$65.80
Purchase #7	$203.66	4.308%	$212.4337	$212.43	$212.45	$212.40
7 purchase totals =	$1,069.35		$1,164.2949	$1,164.29	$1,164.25	$1,164.30