Is it considered forbidden to add an amount to the company's specified rate for money transfer, with the intention of acquiring this added amount?

It is impermissible for an employee to take any portion of the proceeds from the sales of the company for which he works. Any increase in price is the right of the principal, which is the company alone. Even what the buyer gifts to the agent during the contract session becomes the right of the principal, and such an increase is considered an increment in price that accrues to the session.