Hi Kunal,
I am also facing the same problem. At the item level, there is one currency ABC, but at the overall level the amount is appearing in some other currency XYZ.
I have checked the attributes in PPOMA_BBP transaction and found that there are 4 currencies maintained as local currency including XYZ(but ABC not there). None of these 4 currencies is marked as default.
Let me know how can we change the overall currency to start appear in the cart from XYZ to ABC. Is it comming from transaction BP ?