Tips are not automatically added to yur ship account by RCCL. You do have the option of having them added to your shipboard account if you want. You have to fill out the papers and let them know by a certain time, shortly before the cruise is over.
Personally, I prefer to give my tips in the envelopes in cash. Usually, I get the specific amount of cash, and put in one envelope when I leave home. The I have all the correct change I need for the tips. If they give me good service, which they usually do, I can add more into the tip money at the end. I have been on 5 cruises, and never had bad service. I have always tipped over the suggested amount.
Have a wonderful cruise!