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	$91.89	11.669%	$102.6126	$102.61	$102.60	$102.60
Purchase #2	$82.41	6.479%	$87.7493	$87.75	$87.75	$87.70
Purchase #3	$40.29	7.523%	$43.321	$43.32	$43.30	$43.30
Purchase #4	$108.83	13.705%	$123.7452	$123.75	$123.75	$123.70
Purchase #5	$50.65	3.748%	$52.5484	$52.55	$52.55	$52.50
Purchase #6	$62.69	6.554%	$66.7987	$66.80	$66.80	$66.80
Purchase #7	$198.80	13.321%	$225.2821	$225.28	$225.30	$225.30
7 purchase totals =	$635.56		$702.0573	$702.06	$702.05	$701.90