I have used my ATM card at almost all the local banks' ATMs and have never been charged a fee from the ATM, just the S$5 fee for each withdrawal from my home bank in SIN.
FWIW, I have not been charged the ATM fee at UOB Radanasin ATMs either, but my ATM card is issued by UOB Singapore, so I don't know whether they charge ATM fees for other banks.