Well, if your truthful you would. Either you have a conviction or you do not. If you were sent to prison you were definitely convicted. Understandably, people often do not want to list this because if the prospective employer checks it almost always means they won't hire you.
This answer is provided for informational purposes only. Actual legal advice can only be provided in an office consultation by an attorney licensed in your jurisdiction, with experience in the area of law in which your concern lies.
Were you convicted as a juvenile or an adult? The difference may matter. Contact a local criminal defense attorney to have him check your criminal records.
Comments and admissions placed on Avvo are not privileged, be careful and only ask general questions. Contact an attorney to establish an attorney-client privileged communication. Please remember that this is general advise about this subject matter area and should not be construed as establishing an attorney-client relationship or specific advise on your situation.