Answer:
(Fatwa: 902/902=M/1429)
It is concession from you to pay 10% commission to the mechanic for purchasing goods. Islamically, it is lawful to give such commission provided there should be no deception i.e. making the bill with excess money, receiving less money from the mechanic or giving substandard things.
Allah (Subhana Wa Ta’ala) knows Best
Darul Ifta,
Darul Uloom Deoband
