It's unusual to see a compiler internal error with no input file specified (I can also reproduce the same error by providing one). Thanks for reporting this, I'll file a defect report with the developers.
Thanks for the feedback Jeff, I'll add Mac as an effected OS to the developer's problem report.
Apparently icc-14 is the first version to attempt to support -f[no-]rounding-math. icc-13.x just reports it as an 'unknown option'.
At least -frounding-math does work in icc-14:
$ icc -V -frounding-math fp_mantissa.c && ./a.out
Intel(R) C Intel(R) 64 Compiler XE for applications running on Intel(R) 64, Version 220.127.116.11 Build 20140120
Copyright (C) 1985-2014 Intel Corporation. All rights reserved.
Edison Design Group C/C++ Front End, version 4.6 (Jan 20 2014 19:26:22)
Copyright 1988-2013 Edison Design Group, Inc.
GNU ld version 18.104.22.168.2-5.28.el6 20091009