Floating point values have a limited precision. Hence a value might 
not have the same string representation after any processing. That also
includes writing a floating point value in your script and directly 
printing it without any mathematical operations.

If you would like to know more about "floats" and what IEEE
754 is, read this:
http://www.floating-point-gui.de/

Thank you for your interest in PHP.

You are going to want to round() and not truncate here.

Very interesting.
Thank you for your link, I always assumed that this was an issue for old 
languages and that new ones would have corrected the conversion to integer using 
some sort of checking against the "to_string" (I am saying this without knowing 
what it takes or what the code looks like).

As you can see here, the code knows that the value is a float(895), without 
decimals, so the integer should be the same, else I would expect an output like 
float(894.99999999...) during the var_dump.

<?php
$grand_total = '8.9500';
var_dump(                                                            
        $grand_total,                                                
        $grand_total*100,                                            
        round($grand_total*100),                                     
        intval($grand_total*100)                                     
);                                                                   
?>


string(6) "8.9500"
float(895)
float(895)
int(894)

correct misspelled OS

Well, that is just because your output precision is set low enough so when the 
value is printed it prints as 895. Try adding this to the top of your test 
script:

ini_set('precision',32);

And no, this isn't a modern language vs. old language thing. 

For example, in Python:
Python 2.7.3 (default, Apr 20 2012, 22:39:59) 
>>> a=8.9500
>>> print a*100
895.0
>>> from math import floor
>>> print floor(a*100)
894.0

The way to fix this is to use arbitrary precision math routines and every 
scripting language, including PHP (see gmp, bcmath) provides those, but they are 
so much slower than the cpu-provided floating routines that it is hard to 
justify.

I never stop learning!!

Thank you very much !

Wouldn't make sense to have the conversion to INT work based on the precision ?

precision32:
 - intval(float(894.99999999999988631316227838397)) = 894
precision 14:
 - intval(float(894.99999999999988631316227838397)) = 895

That's exactly what round is for. You pass the rounding precision you want as an 
argument.