title: PayPal tax_cart not working with 4 digits decimal number
body: <p>My problem is so weird and it happened suddenly
  if i write my code as follows :-</p>
  
  <pre><code>&lt;input type="hidden" name="tax_cart" value="&lt;?php echo ($total*0.0878);?&gt;"&gt;
  </code></pre>
  
  <p>it doesn't work but if i removed the first "0" like this :-</p>
  
  <pre><code>&lt;input type="hidden" name="tax_cart" value="&lt;?php echo ($total*0.878);?&gt;"&gt;
  </code></pre>
  
  <p>it works fine, any suggestions?</p>