How do online shops send a percentage to their bank accounts, while other part is sent to a seller?

our developers' team are interested in creating an online shop for the company that takes 5% of the cost of whatever item is selling, and then transfer it to company's bank account.

For example: A-customer, B-seller, C-online shop.

A buys a cap that costs $20 so that B gets $19(95%) and C gets $1(5%).

A process should execute automatically. How to manage these operations and What technology should we use? Writing in Ruby on Rails.

Thank you