Rules to validate field group?

I created a content type for recipes. The content type has a field group for ingredients where you can add rows as needed. Once the user goes to save a new node I want to use the Rules (or simular?) module to validate the fields in that the sum of FieldX equals 100% for all rows. I can't seem to find any tutorials or documentation for this use. Is this possible using Rules or will I need to code for it?