We have a Problem with differences in the total price of the order between our Magento Webshop and ERP.

For example Magento (in our case calculates this way:

  • 7.85 € (product price) - 5% (tier disc. for 5 pcs) = 7.4575 € => 7.46 € (will be rounded now)
  • 7.46 € (tier price) x 100 pcs (qty) = 746.00 € (position total)

But our german ERP calculates this way:

  • 7.85 € (product price) - 5% (tier disc. for 5 pcs) = 7.4575 €
  • 7.4575 € (tier price) x 100 pcs (qty) = 745.75 € (position total) => 745.75 € (will be rounded now)

Result for the order item total:

  • Mage: 746.00 € => more or less 5% discount ( 4.97% )
  • ERP: 745.75 € => exactly 5% discount

My reflections:

It could be a solution to...

  • ...increase the precision of the tier prices from 2 decimal places to X
  • ...use percentage tier discounts instead of amounts.


  1. Is there a parameter in the magento configuration to increase the precision of the tier prices? ...or another easy way?
  2. Do you have a recommendation for a module, which allows percentage tier discounts, calulates with all decimal places and rounds the item total at the end?
  3. What are your thoughts?

Thanks and best regards,


  • Too bad, that there is no time to reply. – sv3n Apr 29 at 22:30
  • 1
    See below your answer. :-) – Chris May 2 at 7:44

Also german market ....

That price rounding was a problem since beginning, at least if you work with different tax calculation settings (incl. and excl. VAT for differnt stores).

We solved it with changing rounding to 4 decimals ... just have rewrite two methods:

  • Mage_Core_Model_Store::roundPrice($price)
  • Mage_Adminhtml_Block_Catalog_Product_Helper_Form_Price::getEscapedValue($index = null)

This works for normal prices. Tier/group prices are still displayed with 2 decimals, but are correctly calculated with 4 decimals. If it works for you i can share "mini-extension" code.

Can try https://github.com/sreichel/magento-StackExchange_4DigitPrice

  • Hi @sv3n, there is time to reply, but sometimes I get a little busy. ;-) I think your suggestion can help us, so I asked our developer to take a closer look. Nevertheless, it would be great if you could provide us with the mini extension. Thanks and bet regards, Chris – Chris May 2 at 7:43
  • @Chris added link ... if there are any problem pls raise an issue. – sv3n May 26 at 20:32
  • Thanks! We'll take a look. :-) – Chris Jun 7 at 12:53

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