I think I found the right spot to fix this (haven’t tested on 1.4.0 and it will require further testing, but it’s 2:21 AM my time right now).
in /app/code/core/Mage/checkout/helper/Data.php go to around line 58 and edit the code to be this:
public function formatPrice($price)
return number_format($price, 2, ".", ",");
I followed all of the other steps on the previous thread and made this edit… As of right now, my tier pricing shows up 4 decimals as does my minimum price, but my totals show up two digits.
I’ll need to confirm proper rounding and see how it’s saved in the DB, but this is further along than the previous thread detailed.
Obviously you shouldn’t change the core, you should create a local version, etc.