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	$119.55	6.797%	$127.6758	$127.68	$127.70	$127.70
Purchase #2	$178.58	10.189%	$196.7755	$196.78	$196.80	$196.80
Purchase #3	$206.59	5.780%	$218.5309	$218.53	$218.55	$218.50
Purchase #4	$72.58	9.153%	$79.2232	$79.22	$79.20	$79.20
Purchase #5	$178.85	11.823%	$199.9954	$200.00	$200.00	$200.00
Purchase #6	$30.52	4.496%	$31.8922	$31.89	$31.90	$31.90
Purchase #7	$177.40	8.191%	$191.9308	$191.93	$191.95	$191.90
7 purchase totals =	$964.07		$1,046.0238	$1,046.03	$1,046.10	$1,046.00