The problem is that your perl or C-library is setting (or leaving) the IEEE rounding mode set to RC_CHOP (truncate). Any of the other three modes -- UP, DOWN, OR NEAREST -- would fix this.

The following shows the output on my intel system for teh four modes of IEEE, FP operations:

#! perl -slw
use strict;
use Inline C => Config => BUILD_NOISY => 1;
use Inline C => <<'END_C',  NAME => 'ieeroundmode', CLEAN_AFTER_BUILD 
+=> 0;

unsigned int controlFP( unsigned int new, unsigned int mask ) {
    return _controlfp( new, mask );
}

END_C

use constant {
    RC_MASK => 0x00000300,
    RC_CHOP => 0x00000300,
    RC_UP   => 0x00000200,
    RC_DOWN => 0x00000100,
    RC_NEAR => 0x00000000,
};

print "Setting mode CHOP; controlFP returned: ", controlFP( RC_CHOP, R
+C_MASK );
for( my $n = 0.000005; $n < 0.0001; $n += 0.00001 ) {
    printf "%.15f %.5f\n", $n, $n;
}

print "Setting mode UP; controlFP returned: ", controlFP( RC_UP, RC_MA
+SK );
for( my $n = 0.000005; $n < 0.0001; $n += 0.00001 ) {
    printf "%.15f %.5f\n", $n, $n;
}

print "Setting mode DOWN; controlFP returned: ", controlFP( RC_DOWN, R
+C_MASK );
for( my $n = 0.000005; $n < 0.0001; $n += 0.00001 ) {
    printf "%.15f %.5f\n", $n, $n;
}

print "Setting mode NEAR; controlFP returned: ", controlFP( RC_NEAR, R
+C_MASK );
for( my $n = 0.000005; $n < 0.0001; $n += 0.00001 ) {
    printf "%.15f %.5f\n", $n, $n;
}

__END__
C:\test>ieeroundmode.pl
Setting mode CHOP; controlFP returned: 525087
0.000005000000000 0.00001
0.000015000000000 0.00002
0.000025000000000 0.00003
0.000035000000000 0.00003
0.000045000000000 0.00004
0.000055000000000 0.00005
0.000065000000000 0.00006
0.000075000000000 0.00007
0.000085000000000 0.00008
0.000095000000000 0.00009
Setting mode UP; controlFP returned: 524831
0.000005000000000 0.00001
0.000015000000000 0.00002
0.000025000000000 0.00003
0.000035000000000 0.00004
0.000045000000000 0.00005
0.000055000000000 0.00006
0.000065000000000 0.00007
0.000075000000000 0.00008
0.000085000000000 0.00009
0.000095000000000 0.00010
Setting mode DOWN; controlFP returned: 524575
0.000005000000000 0.00001
0.000015000000000 0.00002
0.000025000000000 0.00003
0.000035000000000 0.00003
0.000045000000000 0.00004
0.000055000000000 0.00005
0.000065000000000 0.00006
0.000075000000000 0.00007
0.000085000000000 0.00008
0.000095000000000 0.00009
Setting mode NEAR; controlFP returned: 524319
0.000005000000000 0.00001
0.000015000000000 0.00002
0.000025000000000 0.00003
0.000035000000000 0.00004
0.000045000000000 0.00005
0.000055000000000 0.00006
0.000065000000000 0.00007
0.000075000000000 0.00008
0.000085000000000 0.00009
0.000095000000000 0.00010
[download]

Maybe you can set the rounding mode yourself in a similar way?