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	$81.33	5.105%	$85.4819	$85.48	$85.50	$85.50
Purchase #2	$241.46	7.422%	$259.3812	$259.38	$259.40	$259.40
Purchase #3	$29.29	6.125%	$31.084	$31.08	$31.10	$31.10
Purchase #4	$113.57	12.405%	$127.6584	$127.66	$127.65	$127.70
Purchase #5	$18.45	12.743%	$20.8011	$20.80	$20.80	$20.80
Purchase #6	$238.68	3.275%	$246.4968	$246.50	$246.50	$246.50
Purchase #7	$232.37	10.424%	$256.5922	$256.59	$256.60	$256.60
7 purchase totals =	$955.15		$1,027.4956	$1,027.49	$1,027.55	$1,027.60