manager is definitly ok with this , i know manybochurim who the manager is on a first name basis with , he always makes sure to take care of good customers.
i tip usually 40-50 shekel on a meal that was max 130.......but i dont tip every night im there , that would be pointless, more like once a week .
thats the way you get service in israel only through tips,
i rember back in the day when the dan pearl was open , i used to be there with my family pesach succos and summer, wow did they take care of you for a few us dollars .