Fix: consider the extra 1 Wei for networkFee

src/modules/dashboard/components/Dialogs/CreatePaymentDialog/CreatePaymentDialogForm.tsx

@@ -119,19 +119,26 @@ const supRenderAvatar = (address: Address, item: ItemDataType<AnyUser>) => (
   <UserAvatar address={address} user={item} size="xs" notSet={false} />
 );
 
+// NOTE: The equation to calculate totalToPay is as following (in Wei)
+// totalToPay = (receivedAmount + 1) * (feeInverse / (feeInverse -1))
+// The network adds 1 wei extra fee after the percentage calculation
+// For more info check out
+// https://github.com/JoinColony/colonyNetwork/blob/806e4d5750dc3a6b9fa80f6e007773b28327c90f/contracts/colony/ColonyFunding.sol#L656
+
 export const calculateFee = (
   receivedAmount: string, // amount that the recipient finally receives
   feeInverse: string,
   decimals: number,
 ): { feesInWei: string; totalToPay: string } => {
   const amountInWei = moveDecimal(receivedAmount, decimals);
-  const totalToPay = bigNumberify(amountInWei)
+  const totalToPayInWei = bigNumberify(amountInWei)
+    .add(1)
     .mul(feeInverse)
-    .div(bigNumberify(feeInverse).sub(1)); // this formula is easily derivable
-  const feesInWei = totalToPay.sub(amountInWei);
+    .div(bigNumberify(feeInverse).sub(1));
+  const feesInWei = totalToPayInWei.sub(amountInWei);
   return {
     feesInWei: feesInWei.toString(),
-    totalToPay: moveDecimal(totalToPay, -1 * decimals),
+    totalToPay: moveDecimal(totalToPayInWei, -1 * decimals),
   }; // NOTE: seems like moveDecimal does not have strict typing
 };