If you have a security setting in Core that doesn't show bill rate and cost rate for employees, it still shows the Charge Amount in Time Entries. Why so?
Core comes with a granular level of security permissions to cover the broader user base with different permission requirements. Some companies, for instance, want to show charge amounts to their employees, but not the cost rates in some screens and reports. So, there is a separate security for hiding the Charge Amount to handle such scenarios. To show or hide this value, uncheck the "Show Charge Amount" permission under Security > Customize/Edit > Time Entry.
You can check Core Help > Security Profiles to know more about each security setting.