As Judy mentioned; technically whether you are registered or issuing receipts or not; you should still be claiming that income. In which case you sort of have to have receipts and paperwork. That being said, I realize that many people earn thier income under the table from this type of career.
I chose to claim everything because I want to have a verifiable income when it comes to banking, lending, etc. I also feel like it gives me an edge over providers who cannot issue receipts to parents. I have a name for my business, but it is unofficial. The cheques are made out to me, personally, and I do my taxes under my own name. I take advantage of all the available tax credits and deductions for a self-employed business person. Therefore, I don't end up losing half of my income to the "man", hahaha.
I did find the government website quite useful. Go to www.cra-arc.gc.ca and search "daycare in your home". It will give you a wealth of info on what they need to see, how to give receipts, and what you can write off, etc!!!
Good luck!