To As of version 2.117 you can configure how many decimals will be used and shown for your Sales Price in all the calculations and for the according surcharges you can follow the steps below.
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After selecting a value between 0 and 9 for the field "Sales Price decimal places" you can proceed with step 2.
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Afterwards enter the number of decimal places you want to see for the currency fields in Salesforce.
The rounding for all the amounts will still apply to 2 decimals as you can read on this Wiki page: 7.5.5.9 Rounding Alert.