body: I understand that if I sell things online, I need to calculate Taxes based on customer location. 
  
  
  Can I use IP(Internet Protocol address) to locate customer or should I ask them explicitly?
  
  
  If it is fine to use IP to identify customer's Country, is it fine to locate customer State/Province. 
  
  
  I need it because Canada has different taxes in different Provinces.
  
  
  
title: Using IP(Internet Protocol address) to calculate Tax