He works in a restaurant and takes tips with the knowledge of the owner
Question

                My father works in a tourist restaurant where there is no alcohol, only food and drink. He gets a share of the daily profits and a monthly salary. 

The tourists come in buses and do not pay the bill after eating; rather it is the tour company that pays the bills for the food. 

During the meal, the bus drivers wait outside. 

The owner gives my father some money every day and says to him: Give tips to the bus drivers. The owner of the restaurant and the owner of the tour company know about these tips, in the sense that is something regular for the owner of the tour company to give the driver a salary and tell him that the restaurants will give him tips. 
And the driver has nothing to do with the tourist groups; rather he is just a driver.

My father also accepts tips with the knowledge of the owner of the restaurant; in fact the owner encourages him to accept them. 
What is the ruling on my father's wealth?.
Praise be to Allah.
      We have previously discussed the ruling on accepting tips 
      and “baksheesh” in the answer to question no.
      82497. 

    But if the tips in this case are given with the knowledge of 
    the tour company for whom the driver is working, there is nothing wrong with 
    that, because the restaurant can give some of the money to the company, so 
    if it agrees to give it to the worker, there is nothing wrong with that. 

    The same may be said with regard to what your father 
    receives: if it is with the knowledge of the owner of the restaurant, there 
    is nothing wrong with it, because the customer has the right to pay more 
    than the agreed price, and if the owner of the restaurant agrees to leave 
    this additional money for the worker, there is nothing wrong with that. But 
    the worker or employee has to do his job properly and give the customer his 
    rights in full, whether he gives him a tip or not. 

    Shaykh Ibn Jibreen (may Allah have mercy on him) was asked: I 
    work for a transportation company and I transport refrigerated fruit and 
    vegetables from Madeenah to Jeddah or Makkah or Riyadh. When I arrive, the 
    one to whom I am making the delivery gives me some money, 100 or 200 riyals, 
    in appreciation for my delivering the vegetables to him quickly. Please note 
    that the owner of the company knows about that. 

    My question is: is this money or tip, as they call it, halaal 
    or haraam? Please advise me, may Allah reward you with good. 

    He replied: We think that there is nothing wrong with you 
    taking the money that the owner of the grocery store gives to you when the 
    owner of the company is aware of that, and the aim behind that is to 
    encourage you to deliver the goods and take care of the vegetables before 
    they go rotten. As you deserve it because of your effort and you taking care 
    of the goods, and as it was given to you willingly by the owner, there is no 
    reason why you should not take it, even if it is in addition to the salary 
    for which you work. The aim behind it is to encourage you to carry on and to 
    do what is in their interests. And Allah is the source of strength. 

    End quote from Fataawa Islamiyyah, 4/347 

    And Allah knows best.