You say goodbye and I say hello

I am sure the Beatles must have come to the Dominican Republic when they wrote that song.

The Dominicans must be the most friendly nation on earth, and whenever you pass someone in the street, the least you do is say "hello" or wrinkle your nose or shake their hand. However, I have noticed that when I say 'hola' the response is "adios" which means goodbye. I suppose there is no less reason to say goodbye as opposed to hello as you are walking past someone, but I am not sure if I am supposed to say "adios" too.

There are a whole range of other greetings. I could say "buen dia" which means good day, or, more likely, shorten it to "buenos". I could say "entonces" which means "so", but you don't wait for the answer. Another option would be "Que dice ese hombre?" which means "what does this man say?" I have heard men use that more than women so I haven't tried that one yet.

Often people will say,"Como va todo?" which is "How is everything?"

But what I really want to know when I walk past someone is if I say hello should the response be goodbye, or hello. And should I say goodbye instead of hello?

Anyone know the answer?