Rounding off rule in GRE

GRE Quant Problem Solving
1

Case 1: If the digit is 0,1, 2, 3, 4 we can just ignore that number
e.g. 13.1234 ==> 13.123
Case 2: if the digit is 6,7,8,9 we can just round off to closest bigger number
e.g. 13.126 ==> 13.13

My question is what we do when the digit is 5, Some sources say that we can round it off like case 2 and somewhere it says that we can ignore it also.
what does the GRE rule say?

2

If the last digit is less than 5 , then round down . If the last digit is 5 or greater , then round up