This solution will display a third currency alongside the two currencies you are already displaying (this is enabled in 'Settings | Business Settings | Options').
To insert the third currency, simply click on a price in the 'Design' tab. You should highlight a layout called something like 'Product Price Including Tax' or 'Product Price Excluding Tax'.
Replace the code in the layout with the following:
<actinic:block PHP='true' SELECTABLE='false'>
priceformat('<actinic:variable name="SecondCurrencyFormat"/>','<Actinic:Variable Name="TaxExclusivePrice"/>', '<actinic:variable name="TaxExclusivePriceAlt" />');
$nExchangeRate = 2.5;
$sCurrencySymbol = "$";
$nDecimals = 2;
$sDecimalSep = ".";
$sThousandsSep = ",";
echo "/ ";
formattedcurrency($nExchangeRate * <actinic:variable encoding="perl" name="ProductPriceRaw" selectable="false" />, $nDecimals, $sDecimalSep, $sThousandsSep, $sCurrencySymbol);
</actinic:block>
Note that this will only work for standard prices and not if you have quantity price breaks.
To insert the third currency, simply click on a price in the 'Design' tab. You should highlight a layout called something like 'Product Price Including Tax' or 'Product Price Excluding Tax'.
Replace the code in the layout with the following:
<actinic:block PHP='true' SELECTABLE='false'>
priceformat('<actinic:variable name="SecondCurrencyFormat"/>','<Actinic:Variable Name="TaxExclusivePrice"/>', '<actinic:variable name="TaxExclusivePriceAlt" />');
$nExchangeRate = 2.5;
$sCurrencySymbol = "$";
$nDecimals = 2;
$sDecimalSep = ".";
$sThousandsSep = ",";
echo "/ ";
formattedcurrency($nExchangeRate * <actinic:variable encoding="perl" name="ProductPriceRaw" selectable="false" />, $nDecimals, $sDecimalSep, $sThousandsSep, $sCurrencySymbol);
</actinic:block>
Note that this will only work for standard prices and not if you have quantity price breaks.