How much should I charge for house/dog sitting?

I’m going to be house and dog sitting for a couple who I am friends with while they are on vacation with their 6 month old. There are three dogs (boxers, if it matters), as well as a few cats. I’m not sure if I’ll be staying there overnight or not. The complicating matter is that the guy is my boss. I was friends with his wife before I worked for him, and I’ve been working for him for three years, and we know each other well enough that he calls me family. They’ll be gone for a week. How much should I ask for?

As a side note, it always makes me feel weird to ask for money. I never know what is considered too much and it makes me nervous that I’m going to be way over charging.