If you are not comfortable doing it, don't.
But, if she is well behaved and you KNOW she will always follow the rules, then you may want to begin leaving her alone for short periods of time, just while you run up the street to a neighbor or a very close store to get one or two items. No more than 10 -15 minutes for a while. That will give her confidence, and you peace of mind, when you see she is capable of doing it. Then you can extend the time. After you've extended the time, you can extend the distance.
When my son was 8, he started asking if he could stay home alone. So I let him, for short times, and short distances. When he turned 9, I began leaving my daughter with him. (she's 3 years younger) They both know the rules, and they both follow them. (no answering the phone or the door, no going outside, no using the stove) If they start to bicker, they go to their rooms until they feel they can work it out. Now that they are 12 and almost 9, I feel very comfortable leaving them alone. We have never had any problems. In fact, now I even allow them to go outside and play in the backyard. They cannot leave the backyard, and they have to keep the front and side doors locked so the only open door is the slider to the backyard. But at least they get to be outdoors.
However, I will add that I still won't let my daughter stay by herself. She is more likely to bend the rules or push the limits than my son is, so I don't trust her to stay alone. With her brother, I know he will keep her in line. So it all depends on the child.