Tax is a complicated beast.
Given we are small team we have opted to make it simple to get our platform rolling and have opted to eliminate this option for the time being.
You are free to insert taxation into the total cost of your listing price or shipping price. Due to this fact, the price advertised is the final sales price for consumers.
How this may effect your individual circumstance we suggest consulting a tax professional.
Going forward we will have a dynamic tax solution, but for now we appreciate your understanding on this.