Going on June 1 for first cruise w/family of 6, DH, DS-11, DDs-10, 8, and 2 and myself. Do you tip per person, does it matter what category or adult vs child? Don't want to be cheap but need to prepare for trip and budget. Also, thought I read you could put tip on cabin bill so it is possible to pay with charge, is this true. Thanks for some guidance.