Rounding decimals?

[Crossbones]

I've been tasked with revising my stores offline point of sale program. Our servers go down regularly, and we need an efficient way to log our transactions offline.

Here's the point: How do I get Fusion 2 (regular edition) to round the change? The C++ book I've got recommends making pennies integers, but man that's a lot of work for edit boxes in Fusion. Correct me if I'm wrong!

This is what I've got so far (I know it's convoluted, I'm hoping it's easier than this). Tax is editable as we have stores in different states, and the "floor" is to cut off superfluous floating points.

Floor(((value( "subtotalnum" )*(Val(Edittext$( "tax" ))/1000.0))+Round(value( "subtotalnum" )))*100)/100

It works fine...if the price of a product ends in ".99", otherwise it's a crapshoot. Is there some function or formula I'm missing? I've searched these forums, and the internet in general and have found little help. Any input is greatly appreciated.

[Dynasoft]

Do you mean to round to whole pounds, or round to whole pennies?

For pennies, I'd expect the following to work:
store (round((1.0+Val(Edittext$( "tax" )/1000.0)*Round(value( "subtotalnum")*100)) as pennies
Set editbox to str$(floor(pennies/100)) + "." + Left$("00",1-Floor(log(pennies mod 100))) + str$(pennies mod 100)

That should construct the number manually, even putting in the extra 0 if pennies is under 10, so you don't get the long decimals from floating point inaccuracies.

I don't have MMF to hand so it might be log10() or log(... , 10) instead of log().

EDIT: oops, it was only adding the 0 if there was more than 10 pennies, try now.

Note: I don't think it likes negative number.