In England...or at least in Northern England, it is quite common to use 'cheers' instead of 'thank you' in less formal situations. I wouldn't say 'cheers' in the bank or in an office but when buying drinks from a bar it is quite common to say 'cheers'. We also use it in petrol stations, newsagents etc unless the assistant is a lot older, then we would be more formal and use 'thank you'. We also use 'cheers' in situations where somebody gives you something or helps you in some way. Imagine if you are walking and drop some papers. Somebody picks them up and hands them to you. It would be quite ok to say 'cheers' in this situation. It really depends on the person and you can use it at your own discretion. You need to decide whether you can be informal or not. You can also use 'ta' :-)