Price variation according to weight in lbs/kg

Hi guys, I need help.

I work with logistics and I'm doing a spreadsheet for automatic cost calculation... It turns out, I use someone else's service that charges by lbs and I need to calculate the shipping cost of a certain product that weighs X lbs.

My idea is to inform the weight of my product in lbs and the spreadsheet to find the closest value according to the price table for the service. But that's where there's another problem... The weight variation of the service doesn't have a standard or average in the table. Below I will send the price list.

h t t p s : / / i . imgur . com/tXkxruA . png

[I separated by space because I can't post links]

Example, my product weighs 12lbs, so excel would do an automatic query and find the value according to the table above. The problem is if my product weighs 12.4lbs.

If anyone can help me develop a formula for this, I would be very grateful indeed.