Calculating Tiered Fees

Hi All,

I am trying to calculate total fees owed based on a tiered system. For example, if we made $35000 in revenue for a client, we would take 30% on the first $10000, 25% on the next $10000, 20% of the third $10000, and 15% on the remaining $5000. I'm currently trying to avoid nested IF statements and I thought that using Arrays in Sumproduct would be the way to go. However, the formula below isn't working out.

=SUMPRODUCT(--(Revenue>$FirstTier:$LastTier),--(Revenue-$FirstTier:$LastTier),%FirstTier:%LastTier)

And here is an example of the sheet.

https://docs.google.com/spreadsheets/d/1bMXdPHHtZADUHHHJukyPOva1owaOLyMA1T8oqBGUbJM/edit?usp=sharing

Is there a way to do this without if statements? Thanks!