Process tolerances should be indicated by your supplier, however below are some general guidelines

Process Tolerances
Process	Tolerance in mm
Drilling and Punching	± 0.5
Grinding	± 0.12
Guillotine	± 1.5
Laser Cutting	± 0.4
Plasma Cutting	± 1
Hy-def Plasma	± 0.5
Gas Cutting	± 2
Plate Forming	± 0.5
Saw Cutting	± 3