In the past when the service fee did include a contribution to the server, it was just $1 only per fee. The " search" facility in threads on this matter here on that forum will cover that.
It was a number of years ago, the top part was removed and the advice changed to " at your discretion.
It was never as high as $5, which when the fee was as low as -$10 pp in the past would be 50% of the fee.
DCL says that the up charge all goes to " contribute to the extra food costs, which are actually above the current fee level.