makes sense
The billing settlement is done in the steps of 300 KB which means that a usage will be rounded off to the nearest integral multiple of 300 KB and will be charged according to the allotted tariff plan.
For instance, 950KB will be divided into three steps of 300KB that comes to 3×300=900 and rest of the 50 KB will be rounded off to another 300 KB and the total billing will be for the usage of 1200 KB.