That is probably just me not noticing the Sales Tax was activated. I am in the Tier you have right now, albeit there only stands and explanation to the Sales Tax and that it is optional, nothing to put a cross in to activate it.
Edit: Sales Tax can only be marked if there are at least two benefits listed which there aren't in the First Tier as I just found out. Are you sure there is a Sales Tax activated? If so I will have to message Patreon and ask about it. Anyway, I am sorry for the inconvenience.