Mmmm it gets tricky with rounds, really is easier to stick to your own if you feel that way or at the very least partner up with one or two others that are on the same or similar priced drinks to you.
Years ago when drinking in pubs didn't require a remortgage (15 years ago) we used to do rounds, but this was when a pint would cost under £3, a round for 7/8 of us watching the rugby from midday till 9pm (six nations) would be like £20 and because we were there all day everyone would buy one mostly, no one would take the pee and order something more expensive on every one else's round etc.
The thing that used to bug me, was within this group that met, a few girlfriends would go, myself included and some of the girlfriends seem to think they were exempt from the round rota? I always brought my round (I was one of the girlfriends) but there was one who never did, sometimes her boyfriend would buy 2 to cover her but as everyone got more tipsy they didn't seem to realise he was just covering her round and would see it as he brought 2 if that makes sense.
Now drinks are so much more expensive, mostly we just buy within our couples when we are out, or if you do buy an extra one as your at the bar, that person is usually decent enough to buy you one back a bit later.