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	$196.26	4.718%	$205.5195	$205.52	$205.50	$205.50
Purchase #2	$193.50	12.630%	$217.9391	$217.94	$217.95	$217.90
Purchase #3	$8.93	13.840%	$10.1659	$10.17	$10.15	$10.20
Purchase #4	$33.80	7.500%	$36.335	$36.34	$36.35	$36.30
Purchase #5	$250.26	6.246%	$265.8912	$265.89	$265.90	$265.90
Purchase #6	$59.90	9.328%	$65.4875	$65.49	$65.50	$65.50
Purchase #7	$117.50	13.109%	$132.9031	$132.90	$132.90	$132.90
7 purchase totals =	$860.15		$934.2413	$934.25	$934.25	$934.20