This is exp table from TRO official. Level 1 – 99 need 677 M Exp for normal class and need 1,957 M Exp for hi-class.

If you want to be normal class Lv.99, You should…
Kill Poring 338,731,866 times.
Or kill Raydric 198,670 times. Or
Or kill Anolian 114,825 times. Or
Or kill Anubis 24,196 times. Or
Or kill Baphomet 6,317 times.

Ro Revo-Classic and ReStart Exp Table

Ro Revo-Classic and ReStart Job Exp Table

See blue background right column.

Ro Revo-Classic and ReStart Hi-Class Exp Table

Ro Revo-Classic and ReStart Hi-Class Job Exp Table

Source : Offical from TRO