I've only sailed on Carnival and they charge the tips to your sail and sign card. You can adjust it up or down accordingly the last night. I believe it's 9.75pp/night on Carnival. That's about 68.25 pp for a 7 night cruise. That doesn't include the Maitre'd which you give them their tips the last evening at dinner.
Here's what they recommend:
Room Stewart 3.50/guest per day
Dining room Team 5.50/guest per day
Dining services Staff .75/guest per day
Maitre'd is at your discretion
What cruiseship are you going on? If it's Carnival they most likely automatically charge it to your total bill which would be a total of 68.25/pp on a 7 night cruise