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	$198.73	10.538%	$219.6722	$219.67	$219.65	$219.70
Purchase #2	$76.31	12.509%	$85.8556	$85.86	$85.85	$85.90
Purchase #3	$58.61	12.295%	$65.8161	$65.82	$65.80	$65.80
Purchase #4	$33.62	5.383%	$35.4298	$35.43	$35.45	$35.40
Purchase #5	$213.58	13.105%	$241.5697	$241.57	$241.55	$241.60
Purchase #6	$219.86	10.779%	$243.5587	$243.56	$243.55	$243.60
Purchase #7	$169.41	4.161%	$176.4592	$176.46	$176.45	$176.50
7 purchase totals =	$970.12		$1,068.3613	$1,068.37	$1,068.30	$1,068.50