Sure, but it may take some script and it can get messy if you have a multi-page site and only want to ask the question about destination once.
For a single item (or asking the user for input for every item ordered) you could use a drop-down (select) where the value of the different options was the amount of tax (for an item costing 10.00...
Select destination for tax -
<select name="tax">
<option value="1.50">Ontario</option>
<option value="0.75">Canada</option>
<option value="0">Non-Canada</option>
</select>
But the TAX field is not changed if the user changes the quantity of the order once inside the PayPal cart window! The obvious problem with this example is that if the guy changes the quantity once he is within the PayPal cart he can bypass your taxes. Unfortunately, PayPal does NOT have a percent tax calculation that may be modified!
If you insist on asking the question just once for multiple items on a page then you need to have some scriping that remembers the answer in global variables and a function that is called for every order to stuff the tax value. But AGAIN, you have the problem of the customer modifying the quantity AFTER he gets into the PayPal cart (no way to detect that!!!!!!!!!)
Worst case - for a single question on a multipage site you probably need to go to a local cookie for memory, functions to manipulate the cookie (load, store) and a function to apply the tax. BUT AGAIN, the user may change the quantity once inside the PayPal cart!!!!!!!!! You have no way to detect either the change in quantities, OR the fact that the user has NOW decided to place the order.
There is but a single way out of this problem, and that is a 3rd party cart (a cart you place between your pages and PayPal which is used only for checkout [credit card validation]).
This question has come up both in this forum, and with my clients. I am going to address it by placing something in my prototype client-side shopping cart to handle it. Give me a day or two...
http://members.aol.com/paypalcart/
Ron.
