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	$203.85	5.725%	$215.5204	$215.52	$215.50	$215.50
Purchase #2	$59.25	12.509%	$66.6616	$66.66	$66.65	$66.70
Purchase #3	$79.32	3.495%	$82.0922	$82.09	$82.10	$82.10
Purchase #4	$229.71	7.247%	$246.3571	$246.36	$246.35	$246.40
Purchase #5	$240.43	3.376%	$248.5469	$248.55	$248.55	$248.50
Purchase #6	$103.31	3.296%	$106.7151	$106.72	$106.70	$106.70
Purchase #7	$48.41	7.634%	$52.1056	$52.11	$52.10	$52.10
7 purchase totals =	$964.28		$1,017.9989	$1,018.01	$1,017.95	$1,018.00