What % of tax revenues should the rich (top 5%) pay?

[RCTjunkie]

I want to be careful into organizing categories for percentages.

For example, if I said 20% for less then 100K, and 30% for more then 100K, what would motivate someone to get a pay raise from 99,000 dollars to 105,000 dollars when in reality they'll lose money?

Maybe just a flat dollar per dollar 23.436% tax rate.