Using ConfiForms Rule and the formula like 

total=([entry.p.transform(price).join(+)])

to calculate the sum for the order

See more about transform function on Virtual functions page



Rows in prices form


Try checking the "p" field - the amount is recalculated.

"p" is the smart field taking values from "prices" form


Storage format for calculation rule

      <ac:structured-macro ac:macro-id="e9724371-0213-48a9-8e1c-6184f4b4e439" ac:name="confiform-field-definition-rules" ac:schema-version="1">
        <ac:parameter ac:name="values">total=([entry.p.transform(price).join(+)])</ac:parameter>
        <ac:parameter ac:name="action">Set expression</ac:parameter>
        <ac:parameter ac:name="actionFieldName">p</ac:parameter>
        <ac:parameter ac:name="onUserActionOnly">true</ac:parameter>
       </ac:structured-macro>