As per Canada Post web site(see below).For items that weigh between 50-100grams.It is very easy to get over that 100 grams,and when you do it changes the postal rate pretty fast.There is no tax if you send registered mail.Any out of country mail that is over $5.00 is tax free.Just so you know if you sent one bubble mailer oversea(England $4.10 plus tax=$4.72) you should always buy one US stamp($1.06) to go with the order.This puts you slightly over $5.00($4.10+$1.06=$5.16) and no tax.Without the stamp you are slightly under and subject to 15% tax(here in Nova Scotia).But now you have $1.06 US postage for only $.44.That is like 60% off that one stamp.Do this a few times and you have enough postage to send a couple bubble mailers at a great savings..
International Letter-post See Postal Guide for Delivery Standard
$4.72
Prepaid
Options
Registered $13.95
Advice of Receipt $1.75
Rate Summary
Base Price $4.10
Coverage* Included
Fuel Surcharge $0.00
Options $0.00
Tax $0.62
Total $4.72