I am the same as most who have posted. Vomiting, 2-3 dirreaha's and/or fever are an immediate pick up. I used to allow them to stay if they were teething and I had permission to give them medicine but it is just too difficult IMO to say it's teething and not a cold so now, fever for whatever reason means they need to be picked up. Some parents don't like it but they don't realize it protects their child from getting something too. If they have a clear runny nose and mild cold symptoms they are allowed but they have to be able to get through the day.
I am paid 2 weeks in advance and am paid whether they are here or not. The only time I give money back for sick days is if I am sick and have to close.