I've reported this problem to the XC5 dev team:
https://bt.x-cart.com/view.php?id=46841
However, a better approach would be using CSS to style your pages.
For example, you can wrap your IMG tags into a DIV tag having "my-custom-class" as the "class" attribute, and then add the following CSS rule via ThemeTweaker:
Code:
.my-custom-class img {
width: 24%;
}