title: Rounding in Swift with round()
body: <p>While playing around, I found the round() function in swift. It can be used as below:</p>
  
  <pre><code>round(0.8)
  </code></pre>
  
  <p>Which will return 1, as expected. Here's my question:</p>
  
  <p><strong>how do I round by thousandths  in swift?</strong></p>
  
  <p>I want to be able to plug in a number, say 0.6849, and get 0.685 back. How does round() do this? Or, does it not, in which case, what function does?</p>