I've read some of the other post and I'm having a similar problem. About 2 days ago my toilets started bubbling and dirty water coming up in the tub and shower when the Washer is in use. The question is, we are connected to the city's sewage system, do we have a septic tank that could be baking up also?

No, if you are on city sewer there is no septic tank ( should not be anyway)

It sounds like you have a partial clogged sewer line somewhere