Wrong discount value calculation

Hi Expert,

               We are using SAP B1 8.81 Pl-10, During PO entry we have entered Discount value but after calculation it's showing wrong value.This is happening only when we are using unit price as second decimal value between 0 and 5 like 0.51,0.52,0.53,0.54,0.56......

here I have attached Screen shot also which has clear information.please any one suggest me what is the solution.

Thanks & Regards

Alok Kumar