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	$193.74	7.358%	$207.9954	$208.00	$208.00	$208.00
Purchase #2	$189.81	12.747%	$214.0051	$214.01	$214.00	$214.00
Purchase #3	$138.85	3.827%	$144.1638	$144.16	$144.15	$144.20
Purchase #4	$132.32	8.491%	$143.5553	$143.56	$143.55	$143.60
Purchase #5	$111.70	6.411%	$118.8611	$118.86	$118.85	$118.90
Purchase #6	$178.70	6.697%	$190.6675	$190.67	$190.65	$190.70
Purchase #7	$39.66	6.577%	$42.2684	$42.27	$42.25	$42.30
7 purchase totals =	$984.78		$1,061.5166	$1,061.53	$1,061.45	$1,061.70