title: check if money is in .99 cents increments
body: <p>On some sites you can sell your item in .99 cents increments. I'm trying to validate if money is entered that way. Example:</p>
  
  <ul>
  <li>0.00</li>
  <li>0.99</li>
  <li>1.99</li>
  <li>2.99</li>
  <li>3.99</li>
  </ul>
  
  <p>Etc.  All ending in .99 cents unless free. So if someone entered <code>1.79</code> it would fail the check.</p>
  
  <p>I was thinking Maybe substring/text hacks or division. Just kinda wondering how something like this could be done the best way for inputting. Like if someone wanted this pricing structure on their own site. Not asking for the full thing. Just need some pointers.</p>
  
  <p>I'm thing so far:</p>
  
  <pre><code>&lt;?php
  function is99($money)
  {
      if (!valid money)
      {
          return 0;
      }
      else if (ends in 00)
      {
          return 1;
      }
      else
      {
          ????
      }
  }
  
  if (is99($_post['price']))
  {
      //allowed
  }
  else
  {
      die('Price isn\'t in 99 cents increments. Please check the example.');
  }
  ?&gt;
  </code></pre>