Rounding for currencies without cents

Hi Aronium team,

So far Aronium has been a great tool for my small bussiness, but sadly there's something missing and it's making me lose money.

The rounding function only works with cents and small amounts, like 5 and 10 units (dollars in most countries), but in my country we don't use cents at all, our smallest coin is 100 PYG, and nobody wants these, the smallest coin people actually use is 500 PYG. 

For example: 1 can of Coke is 6350 PYG, we round that to 6500 PYG.

What I need is pretty simple, adding bigger numbers to the round function, like 100 and 500.

I made an image to explain myself

That's it and thank u for making this tool.