I always give a firm NO. This is because I was once asked for cash for food from a beggar just as I exited a sandwich shop, I offered him the sandwich and he refused. I asked why and he insisted it was money he wanted and I refused to subsidise his liquid diet.
I was also accosted by an Eastern European immigrant who shoved a A4 sized piece of card in my face which read "I am Romanian refugee, I don't speak English. I have no money or food, I have baby to feed, pelase give kindly'. Now, given that I used to work for Social Services I knew this was nonsense so my answer was 'Sorry but we've got enough beggars of our own without you joining their ranks too'. Her answer, given that she claimed not to understand the lingo was '**** you Nazi' and she stormed off. Bloody chancer.