How make different template for each tag (tag.php, tag-1.php)?

Hi!
When I want to edit the template of a category, i make a file of this type: category-ID.php
Example: I have the category with ID=5 and i make a file “category-5.php” and so the category “5” has a different template.

Now, I would do the same thing for the template of tags(tag.php), so that some tags have a different look.

If i make a file “tag-15.php”, it doesn’t work.

Have you some ideas, and, this is possible?

Thanks and I’m sorry for English