GPI makes RFID embedded chips (and jetons / plaques too, I assume). See their webpage at:
http://www.gpigaming.com/rfid-technology/rfid-in-casino-chips

Note that they sell 2 versions of RFID: Low frequency (125 KHz) and High Frequency (13.56 MHz).
They also sell readers / counters for use at tables and casino cages.

It's my understanding that some casinos have purchased RFID chips for higher denominations -- not $5 and less, but beginning with $25 or $100 and above. Wynn was one casino mentioned a few years ago.

It is possible to buy a hand-held RFID reader to check for a signal coming from chips. I haven't tried it, but it should work. These are standard, public frequency bands, used for inventory tracking, etc. Here's a reader that can be plugged into a smartphone, and it reads the correct frequency (13.56 MHz) for the High Frequency signal used by GPI ... only $70.

http://www.rfidshop.net/dthinksl110-high-frequency-hf-rfid-reader-p-704.html

Though I would be curious to try, I think Casino Security might take notice of anyone scanning their chips on the casino floor, and I'd prefer not to be escorted to a windowless room in the bowels of the casino, in order to explain that I was just "curious" !!!!