Pay shipping cost for third party

Hello,

How could i exclude the shipping cost in Customer Invoice?

Example:
I sell an 1 x Apple at $20
Customer pay shipping cost at $5

Totally, Customer will pay $25 to my shop.

i have to pay third party shipping company $5
Totally, i receive $20.

How could i make it works ? Is there anyway to exclude the shipping cost in company incoming? or split them?

Thank you.