Questions about Multiple item shipping per weight

Open Cart - Version 1.5.1.3

I have been having trouble with the Weight Based Shipping option. I have created a world wide shipping option as well as using the uk and us shipping option. I have read up on quite a few forums for my answer. The trouble is in my ratios of weight:cost. When I put in the option 1:17.00 1 being a pound and 17.00 being the cost it does not show up in the checkout options. Now I read up on one of these forum post that if I did something like placing 999 instead of 1 like this; 999:17.00 it does then show up in my shipping option via the checkout. However, the issue I am having is if I add multiple items to the cart like 5 t-shirts. It will calculate the weight of all items combined and just charge a single $17.00 for all 5 shirts. That is too low of shipping it needs to calculate the number of items in the cart and give it the correct shipping according to weight. When I try anything but the 999:17.00 it will not show up in the shipping option via the cart. How do I get the options read something like if they buy one shirt it will be 17.00 to ship, then another 10 dollars per item to ship after that? I tried doing something like 1:17.00,2:27.00,5:57.00 but it did not work for me. Could someone shine some light on this for me?

You are using weight based shipping, yet your description indicates that you are trying to use it for item based shipping.

1:17.00 says the combined package will cost $17 to ship until the weight of the order exceeds 1 pound. 999:17.00 says that the combined package will cost $17 to ship until the weight exceeds 999 pounds.

If you want to charge $17 for the first pound, for example, and $15 for the second pound and $13 for the third pound you would enter 1:17.00,2:32.00,3:45.00.

If you want to apply item based shipping you will need to use an extension that serves that purpose.