Tealium iQ

Add the tag through Tealium iQ, with a JavaScript Code extension.

Not every tag manager keeps a script tag’s attributes as you wrote them (Google Tag Manager strips the data- ones), so add the tag with a few lines of script instead, with your domain in place of example.com:

<script>
(function () {
  var tag = document.createElement('script');
  tag.async = true;
  tag.setAttribute('data-domain', 'example.com');
  tag.src = 'https://fiveb.ar/js/tally.js';
  document.head.appendChild(tag);
})();
</script>

Add a JavaScript Code extension, from the Advanced tab of the Extensions Marketplace, with its scope set to Pre Loader, which runs once on each page. Paste the script without its first and last lines, then save and publish to your production environment. See Tealium’s help on the JavaScript Code extension.

Once it’s live, check it works.