ceil support for calculated units?

I don't know if it was already suggested, but...

<!-- let's say the window is 801px wide -->
<div style="width:801px">
     <div style="width:50%;background:red;float:left;">a</div>
     <!-- annoying pixel line in the middle -->
     <div style="width:50%;background:red;float:right;">b</div>
</div>

<div style="width:801px">
     <div style="width:50%;background:red;float:left;">a</div>
     <div style="width:ceil(50%);background:red;float:right;">b</div>
</div>

"width:floor(50%)" is the default behavior and it equals to write 
"width:50%" so it isn't really needed

I haven't more use cases, do you have any, especially for newer layout 
modules?

Giorgio