High-Rise Handlebars

I need to change the handlebars on my bike so that I'm sitting straight up. (I have RA and my hands and wrists can't handle the pressure of a forward lean onto my current bars.) I have a Roll step through, basically this bike if not this exact one. I could order something online and install it, but I don't know what size to get, and I'm not sure how to determine it.

I live in South Mpls, so I was thinking I could just ride over to Tangletown or Angry Catfish today and get some advice or measurements for what I need to order. I doubt any shop has them in stock. Any suggestions for where I should go, or where I should avoid? Thank you in advance!