Detailed Instructions: Generate the answer for a given question. The question requires common knowledge of English. Make sure that the answer is in detail, long, consistent with the context, and requires general knowledge of English. To be less repetitive, please vary your language for each question. Give a proper explanation to answer, and if necessary, provide the definition of various terms. And conclude your answer if it's long. If you have used other resources (e.g., Merriam Webster's.) to answer the question, include citations in your answer. You don't need to paraphrase the context of your resources, but make sure that your answer is consistent and complete.
Q: Imagine you're in a bar and order a pint of beer, which is 3.20. You only have a 10 note but want to tip the barkeeper. As you can't use 'keep the change' for obvious reasons, what do you say to tip the barkeeper 80 pence, making the total price 4?.
A:
I am occasionally in the same situation when I want to tip a taxi driver. Converting to your problem, I would say: Make it 4 pounds. or if that is not clear: Make it 4 pounds and keep the difference. This is in my country (Australia) where tipping is uncommon, however. Edit: Thinking about it even more, sometimes I add the word 'Just' to the front of the sentence. Not sure why.