The IMF approves the rate and releases it through the BIS to all the Central Banks of the world. This is a highly tested and very automated process. It goes like this.
1. CBI Seeks Approval from IMF ( and we assume key allies) for a rate change
2. IMF approves
3. CBI Releases the rate to the IMF
4. The IMF approves the rate and releases it to the Bank of Intl Settlements (BIS) The BIS is the IT / Computer arm of the IMF
5. BIS post the rate in their system
6. All Central Bank's Computers (including the FED Reserve) constantly query the BIS computer for changes in Rate
7. When Central Banks computers see a rate change they internalize the changed rate and go through their own approval process.
(this may be different from country)
8. We presume the FED and UST pick up the rate and approve it
9. The FED then post the new rate in its computers for in-country banks to query and pick up.
10. US Banks pick up the new rate and change their internal exchange rates as may be their policy.
This is not a complicated process! Central banks ping the BIS - The BIS does not PUSH the changes to the central banks.
Of course it is more detailed than this, but I thought you would like to know the RV flow chart from a low earth orbit level.