In Pos bill IGST Amount has been deducted without mention Customer GST Identification No.At this moment IGST amount deducted if you select POS invoice in which GST State select for customer other than POS Site state then IGST will be calculated.
So, we have locked an ticket in Ginesys portal which id is 129640 & they suggest to lock an idea regarding this matter.
There is a user policy, please find attached the screen shot. You can set it to Local if you intend to calculate CGST/SGST.
We are marking this issue already exists.