I suppose it depends on what the question on the application form said,if there was one, and how you answered it.
I know in the UK the wording on application forms differs. On some you don't have to declare spent convictions which DUIs become after a period of time. Some don't ask about motoring convictions so you don't have to mention them. Some ask for full disclosure including spent convictions but these would not usually be asked for a sales role.
If a question is not answered honestly and a background check reveals the truth I imagine they would not hire due to honesty issues. As you have been honest or not been asked the question I'm sure you will be fine. I hope you are successful. I have a DUI from many years ago and know how hard it is when the past comes back to haunt us. Wishing you the best of luck