Redmine

I was wondering if there was a way (or perhaps a plugin?) that would allow a user to log time as a specific role for a project.

For example, one particular project (MyProject) could have the following types of users:
- Manager
- DB Programmer
- Web Programmer
- Researcher
- System Admin

One person could be any (or even all) of these. The reason behind this is, for example, I charge different rates for different development types.

So let's say I spend 2 hours on database development, 3 hours on web development, 1 hour researching, and 1 hour maintaining the system - I want to log all of this as different roles. This way it would be much easier to separate these roles so I can collect all of my hours on a per-role basis, and quickly calculate how much to charge.

Is this possible? Is there a way I can add a field to the logging where I can select which role I want to log as? Also, it would be preferable if these development types were unique on a per-project basis (since not all projects will have a DB or Web developer, for example).