update:
Think of it like this: decimal floats are inaccurate too, since they can't represent a rational number like 1/3 in finite notation:

1/3 = 0.333333333333333333....
[download]

If all arithmatic was done using decimal notation, assuming a maximum of 10 places you get:

$x = 1/3; #  0.3333333333
$y = $x * 3;
$y == 1 -> false  # $y == 0.9999999999
[download]

The same thing happens here, only since humans have a hard time thinking in floating binary, it's much harder to predict where.

Ok, well since I've had to do most of my financial calculations in PL/SQL in the past since I was dealing with Oracle Financials, I thought I'd try it out:

create or replace function test return varchar2 as
begin
  if (8.78 * 100 = 878) then
     return 'ok';
  end if;
  return 'not ok';
end;
/
[download]

SQL> select test from dual;

TEST
-------------------------------------------------------------------
ok
[download]

They're dealing with binary and decimal conversions. Now granted, I've had to deal with rounding errors in the past, but not for trivial calculations like the one above. I still contend that in this example, where we're not dealing with repeating numbers, that a language should be able to get it right