How to lock down an iPad in Kiosk mode for check-in, event registration, and giving.
There may be some third party apps that help with this, but you might start with the built in functions in iOS and Safari. For example on the iPad under Settings / General there is a Restrictions option you can turn on and inside of the settings for Safari you can restrict which websites are allowed and you enter a 4 digit code to protect it. If you try to navigate to a restricted site it prevents you and prompts for the code. In conjunction with that you could run the iPad in what they call Guided Mode where you would have Safari as the one app that's allowed. The link below talks about Guided Mode and so the combination of Restrictions and Guided Mode might get you what you are looking for and it may be that even with an app that you purchase it will still need to be in guided mode to prevent them from certain things not accessed through the home button.
Below is a list of sites to add when using Kiosk mode for giving and restricting websites using Safari on an iPad.