Under the old “Single Audit” legislation for entities receiving more than $100,000 Federal Funds in a year, their financial statements must list all Federal Funds received and be foot noted.
If you get the audited financial report for each of the sanctuary cities it should give you the mix of all Fed Funds received from all sources.
For example you can see that the City of San Francisco (a sanctuary city) received $465 million in 2015 and $416 million in 2016 in revenue from the federal government per page 28 of their audited financial statements.
I would need to look further to determine how much of the state revenue of $776 million was actually flow through from the feds.
Trump is carrying a BIG STICK.