Custom options price javascript is executed even when these are 0.00

[f1-outsourcing]

I was trying to apply some price formatting by changing this file[1]. Then I noticed that javascript was 'undoing' my formatting, and this was only happening at products with custom options. I think this is related to the price you can give to a custom option. But if this price is set to 0.00, then of course nothing needs to be executed/calculated.

[1]
app/design/frontend/rwd/xxx/template/catalog/product/price.phtml