As long as a workbook is open you can directly refer to it by its name.
Workbooks("workbook name")
etc.
Since you open the workbook with Sheets("sheet1").OLEObjects("SalesFile").Activate
the workbook related to the object will then be opened as a file called "Worksheet in your current workbook". You can therefore use:
Dim wb as workbook
Sheets("sheet1").OLEObjects("SalesFile").Activate
set wb = Workbooks("Worksheet in " & ThisWorkbook.Name)
Thisworkbook.sheets("Sheet1").Range("A1").value = wb.sheets("Sheet1").range("A1").Value 'etc. etc.
wb.Close
Thisworkbook
is a handy tool here, as it will always refer to the workbook the macro is in, despite which workbook is currently active.