Product tax codes for Amazon

Hi i tried to add product tax codes on amazon but it wasn't in the drop down menu like i read in the amazon help link. Is this something i need to worry about?

Also i tried putting this in the amazon forum but strangely it wouldn't allow me to post. I couldn't click the post button[strangely it was grayed out] but could click on cancel.

Not sure what is going on there, best to contact Amazon support to sort that out for you :).