User selects to view Report by Units/Empl/State- how to optimize query when selecting U/E/S (3 if statements)

Question

I have a stored procedure in which the user selects to view sales by either Units / Employees/ State (in the real application there are 10 options)

This inserts into a #temp table via the following logic:

if @ReportOption = 'Units'
begin
    insert into #Sales 
        (
        OrderID,
        CustomerID,
        OptionID,
        OptionName
        )
    select 
        OrderID,
        CustomerID,
        isnull((select UnitID   from Orders o where o.OrderID = t.OrderID),0),
        isnull((select UnitName   from Units u where o.UnitID = u.UnitID),0),
        from #temp t 
end

if @ReportOption = 'States'
begin
    insert into #Sales 
        (
        OrderID,
        CustomerID,
        OptionID,
        OptionName
        )
    select 
        OrderID,
        CustomerID,
        isnull((select StateID   from Orders o where o.OrderID = t.OrderID),0),
        isnull((select StateName   from [States] u where o.StateID = u.StateID),0),
        from #temp t 
end

Is there a better way to do this please? In other words, replace the 10 "if" statement with something more efficient.

It is just the 3rd and 4th column that could change based on one of 10 report options that the user can select.