USPS Shippimg Module same price for 1 to 20 items

[tazzmann67]

I am working on a store for a customer and they recently asked me to add the usps shipping option. I am running joomla 15. and usps module 4.2. all seems to look ok until i hcnage the quantity of items from 1 to 2 or 3 or 10 ro whatever. it still returns the same shipping rate as 1 item. I need help on this ASAP, if anyone has any ideas id really appreciate it very much.

[seyi]

USPS shipping module is based on weight.  So if x number of the items do not pass the weight threshold then they would be the same price.

[tazzmann67]

OK so maybe I am looking for my answer in the wrong place. I am wanting to use the USPS flat shipping rate for one of my customers. it seems that the flat rate shipping is cheaper than UPS or FedEx and will hopefully generate more sales if the "total cost" is cheaper with USPS shipping. However the problem I am having the this is....no matter how many items I add to my cart the shipping price does not change. How can I make a change that would take the dimensions of the item and be able to tell if it fits in that flat rate shipping box then it ships at "X" price but if it exceeds that size\cube then it requires and additional box and price accordingly.
Any help is greatly appreciated.