When providing estimate for software development, are QA hours paid by the same rate as development, or by a different rate?

Lets say we tell our client that we work for $20/h as software developers. Lets say that this project will take 100 hours of development, and another guy in our company is going to need 20 hours to QA the product (and a manager is going to need 10 hours to manage the project)

Now, do we charge them for 130 hours * $20 or do we charge them for 100 hours * $20 and then 20 hours * QA_rate and 10 hours * Manager_rate?

I looked at this SO question, but nothing is mentioned about money: estimating of testing effort as a percentage of development time