Hi sjk,
Technically all tables in Method support tags, if you want to add tags to your "Customer" table, you must first add the "TagList" field to your table. I have provided you with a link here, this is our article on tags, and we make this comment under the section "Creating a tag for another table". Keep in mind, if you do add the "TagList" field on another table, just note that you have to use new tags, they you can't use the tags from your Contacts Table from the Customer Table.
After adding your "TagList" field to your Customer Table, you would then have to add this field to one of your screens, likely your "Edit Customer" screen. I hope this helps, let me know if you have any additional questions on this.
-Ben