Kevin,
I understand the UPS and FedEx requirements of only allowing integers to be passed to calculate shipping cost.
But, let me take you back to the good old' days of Smith Cart version 4.24 (we have this version running for a client right now). Back in the days of version 4.24 only ounces were allowed in the product weight no matter what you picked for your shipping method.
Our client has some products that are 8 ounces and some that are 24 ounces, thus the cart is calculating pounds by dividing the weight by 16 and coming up with 0.5 pounds and 1.5 pounds. My guess is in version 4.24 these weights are being rounded up or cut down to an integer. I assume that if the total shipping weight of an order in cart version 4.24 is less than 1 pound the cart passes UPS or FedEx a weight of 1 pound. I would also guess that if the weight was 1.5 pounds in cart version 4.24 the 0.5 pounds is cut off and only 1 pound is sent to UPS or FedEx.
Please look at this older code and see if you can provide a hot fix, you've somehow lost functionality in the newer cart versions.
Thanks again,
Darren