title: Add variable to Magento session from javascript
body: <p>I have a Tax-toggle button on every page of a Magento store, and want to remember the settings that the user chooses.</p>
  
  <p>The toggle works using javascript, and successfully changes all prices on the page. </p>
  
  <p>However, I would like to remember what they have chosen and the Magento session seems like the ideal way to do this. Is this something I can achieve from javascript? Would the only way be to have it call an external php script?</p>