title: Can C#'s string currency format optionally up to 6 decimal numbers?
body: <p>With a quick test C#'s currency format doesn't appear to support optional decimal places.</p>
  
  <pre><code>CultureInfo ci = new CultureInfo("en-US");
  String.Format(ci, "{0:C2}", number); // Always 2 decimals
  String.Format(ci, "{0:C6}", number); // Always 6 decimals
  </code></pre>
  
  <p>Trying to customize it doesn't work.</p>
  
  <pre><code>String.Format(ci, "{0:C0.00####}", number); // two decimals always, 4 optional
  </code></pre>
  
  <p>Is it possible to use the currency format with an optional number of decimals?</p>
  
  <p>e.g. $199.99 or $0.009999 or $5.00 are shown like this.</p>