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	$217.86	7.203%	$233.5525	$233.55	$233.55	$233.60
Purchase #2	$87.32	9.299%	$95.4399	$95.44	$95.45	$95.40
Purchase #3	$157.75	13.231%	$178.6219	$178.62	$178.60	$178.60
Purchase #4	$19.49	10.412%	$21.5193	$21.52	$21.50	$21.50
Purchase #5	$102.88	8.111%	$111.2246	$111.22	$111.20	$111.20
Purchase #6	$147.74	11.652%	$164.9547	$164.95	$164.95	$165.00
Purchase #7	$246.43	8.456%	$267.2681	$267.27	$267.25	$267.30
7 purchase totals =	$979.47		$1,072.5810	$1,072.57	$1,072.50	$1,072.60