I also use that as I am doing 26+ computers on a regular basis. Compressed air canister with keys facing down followed by a foamy specialist plastics degreaser on a cloth. It is amazing what manages to get in a keyboard, often paperclips and staples prevail but sometimes mints and crisps. I was glad when we went over to touch screen tills a couple of years ago, made life a lot easier and halved my maintenance program