Patreon has changed their minds and decided not to roll out the planned changes for now. More details here: https://blog.patreon.com/not-rolling-out-fees-change/
Should there be further changes to the payment scheme I may update this userscript, but for now it should be disabled.
Calculates the new patreon pledge amount
Download Tampermonkey or Greasemonkey and then open the raw userscript file and hit install.
Note: There is currently a bug preventing Greasemonkey from installing scripts from GitHub. Chrome and Tampermonkey are recommended for now. Firefox users can install from Greasy Fork