Currency round up

I have a currency converter on my site. but the problem is, when people from other countries view it, it shows a silly price.. For example, A product might be $ 19.99 or .49 or .25 in USD. but when someone from Australia views the price its $ 28.91 or just completely silly numbers that look a bit funny.

I want my prices to automatically round up to a better price.

The script I used is below, can someone please help ?