Oncology: is there a commonly used cancer chemotherapy medication/treatment that usually does not result in one loosing their hair?

Depends. It depends on what the underlying cancer is. There are drugs which do not cause hair loss or alopecia.
Yes , but. Regular chemotherapy drugs that directly kill cancer cells , also act on sensitive hair follicles in most of the people, causing temporary loss of hair , how ever hormones and hormone blocking agents will not result in hair loss .
Sure. While some chemo drugs (like adriamycin (doxorubicin) or cisplatin) will almost always cause hair loss, some do not (especially the newer targeted therapies). The thing is, hard as losing hair may be, i'm not sure it should be the deciding factor in choosing the chemo to use. There are well established and effective protocols for common cancers and if hair loss is a side effect, well so be it.