I have to be honest I have never tipped them and I am a generous tipper for everything usually! I would not leave more than $10 regardless if your spend.
Can I also ask. Did you leave your resort address for your address and how did you leave your mobile number? I last used the site a few years ago and I was struggling with it the other day.
I left the address of the house we are staying at and my phone number was set up from the last time we went so I didn't need to change that, but it is listed as +1 77 0096........... on their information.