Sales info off for employees.

I want to be able to turn all the sales info off and all the financial information off but still have my employees be able to write an invoice and add times to tickets.  They see the sales info and not the expenses and think we are making all this money but don't see what we pay in taxes and expenses. How can we turn this off. I have tried to modify the user but you still see the sales info.  and if you take too much away you are not able to use line items. This is a must fix for me. I don't need my employees to see everything that is going on.  PLEASE HELP!