"What If" slicer in a pivot table with actuals How?

[Purplehazed]

I have a simple pivot table that categorizes checkingaccount activity like this:
Paycheck 100 100%
Grocery -10 10%
Rent -5 .05%
Gas -5 .05%
Etc…
Total 80 80%
A power query conditional column categorizes the activity likethis;
ContainsEmployer then Paycheck
Contains Krogerthen Grocery
Contains EZ Gasthen Gas
Etc…

I want toadd a slicer than lets me choose “what if” Paycheck amounts
while theother categories remain actual. Thiswould allow me to
see categoryspending percentages at different earning levels.

Thoughts onDAX functions and/or how best to model this scenario would be much appreciated!