Ok, I'm back with Canadian shipping costs for you, Dangles.
up to 1lb = $19.00
1lb 1oz - 2lb = #20.75
2lb 1oz - 3lb = $22.50
3lb 1oz - 4lb = $24.25
4lb 1oz - 5lb = $26.00
So of course, the more you buy at one time, the better shipping rate. Notice, the first up to 1 lb is $19. But the next pound is just $1.75 more.
Anyhoo, this is common for shipping rates. The first unit is always the greatest because it includes the dimensions of the box plus up to 1 lb. Then when you add extra weight, it just increases the price based on the greater weight only.