Where did you get this idea that you only have to report PART of your tips??? Tips are income and you have to report ALL of it.
According to the IRS:
"All tips you receive are considered income and are subject to federal income tax. You must include in gross income all tips you receive directly from customers, tips from charge customers that are paid to you by your employer, and your share of any tips you receive under a tip-splitting arrangement with fellow employees. The value of cash tips, such as tickets, passes or other items of value, are also income and are subject to tax. If your employer reports allocated tips in Box 8 of your Form W-2 (PDF), you must file Form 1040 (PDF) to report them. Include the allocated tips in your gross income unless you have adequate records to show that you received a different amount. Do not include as a tip any service charge that your employer adds to a customer's bill and then pays to you and treats as part of your wages.
If you receive tips of $20 or more in any one month from any one job, you must report the total tips to that employer by the l0th day of the next month."
Source:
http://www.irs.gov/file/display/0,,i1=52&genericId=16194,00.html
"Your employees who receive tips of $20 or more in a calendar month, while working for you, are required to report to you the total amount of tips they receive. They must give you written reports by the tenth day of the month following the month they received the tips. Employees who receive tips of less than $20 in a calendar month are not required to report their tips to you for that month.
Employees must report to you tips received directly from customers, tips from other employees, and tips that customers charge to their bills. Service charges that are added to a bill and then paid to your employees are not considered tips for tax reporting purposes."
Source:
http://www.irs.gov/file/display/0,,i1=52&genericId=16283,00.html