When creating a limit order in terms of a set dollar amount as opposed to metal ounces, the executed order total may differ from the original estimate, as the transaction may only be executed to align with a metals position out to three decimal places. This may result in a lower final order total than the estimated order total.
Additionally, limit orders will execute at your target spot price, or better. For buy limit orders, this may result in a final order total that is lower than the estimated order total. For sell limit orders, this may result in a final order total that is higher than the estimated order total.