Even before getting to the main point, bringing that money into USA as a traveler / visitor will be a hurdle as a threshold exceeding $10,000 must be declared upon entry. Will they allow the entire 5000 OMR stack in or would that be confiscated even when declared?
Like this: after paying for the food in $, suddenly giving them more money: I’m only a visitor (as I only have foreign currency, i.e. Omani Rial in cash) being like, “Here is 5000 OMR ($13,020) for your efforts” so despite that being a lot of money, will they take it?
The only place where such kind of tips are accepted is the really expensive hotels.
Among normal people, nodody would take you for serious, nobody would believe this is real money etc.
People would curse you, tell you to go away, or worse.