induced nausea and vomiting
is a common problem. There is no specific therapy that works for everyone, but there is a wide variety of therapies that have been shown to work. I would recommend talking to her oncologist
--even if the medications she is on right now are not working well enough--her oncologist will likely have other medications to try. The other reason to discuss this with her oncologist is that occasionally intractable nausea is a sign of a serious gastro-intestinal tract problem that needs evaluation.
To answer your question--yes, it is possible that ginger could held with the nausea. In small studies with ginger powder on top of the standard anti-emetic (that is anti-nausea) regimen--people have shown that the ginger powder helps severe nausea. A more definitive study to see if this effect is real is still ongoing--however initial trials are positive.
The big question with any intervention is the risk versus the benefit. While the benefit appears to be there (as discussed above), the risk seems minimal. Ginger, a natural substance, probably has little side effects. I would however caution over using a large, unnatural amount of any substance.
Overall, it might be worth a shot. That being said, talk with your oncologist about any specific interaction this could have with the chemotherapy or other medicines.