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	$218.43	9.173%	$238.4666	$238.47	$238.45	$238.50
Purchase #2	$183.45	3.210%	$189.3387	$189.34	$189.35	$189.30
Purchase #3	$94.47	11.722%	$105.5438	$105.54	$105.55	$105.50
Purchase #4	$41.59	6.646%	$44.3541	$44.35	$44.35	$44.40
Purchase #5	$11.46	8.706%	$12.4577	$12.46	$12.45	$12.50
Purchase #6	$232.38	11.786%	$259.7683	$259.77	$259.75	$259.80
Purchase #7	$177.65	11.479%	$198.0424	$198.04	$198.05	$198.00
7 purchase totals =	$959.43		$1,047.9716	$1,047.97	$1,047.95	$1,048.00