Rounding off formula on gst

I am giving example : ...

1)      Taxable Value Rs. 54670/-   @ GST 18% = Rs. 9840/60 -----------------

  CGST 9% = Rs. 4920/30 = Round off  Rs. 4920/- ---------------------

 SGST 9% = Rs. 4920/30 = Round Off  Rs. 4920/- ---- Total Rs. 9840/- >>> i.e. 60 paise shortage as per Total 18%

    2)     Taxable Value Rs. 54670/- @ GST 18% = Rs. 9840/60  = Round off Rs. 9841/- ---

            CGST 9% = Rs. 4920/30 = Round off Rs. 4921/-

          SGST  9% = Rs. 4920/30 = Round off Rs. 4921/- ----  Total Rs. 9842/- >>>>> i.e. Rs. 1/- excess as per total 18%

Question : Where is require to Round off at Gross GST 18% OR  at break up  9% & 9% --- 

Also let me know what formula is correct between above ---- No. 1. or No.2

Please reply the above two nos questions ... thanks