When the digit to be discarded is exactly 5 and is followed only by zeros, the usual convention followed in NCERT texts is to:
a) Always increase the preceding digit by 1. (Round 5 up)
b) Adjust the number so that the preceding digit becomes even (increase it by 1 if it is odd).
c) Adjust the number so that the preceding digit becomes odd (increase it by 1 if it is even).
d) Always leave the preceding digit unchanged.