Hello Inayat,
You can set tolerances for MIRO processing. For details, read SAP Help:
http://help.sap.com/erp2005_ehp_07/helpdata/en/78/70b6531de6b64ce10000000a174cb4/content.htm?frameset=/en/ea/71b6531de6b64ce10000000a174cb4/frameset.htm¤t_toc=/en/ea/71b6531de6b64ce10000000a174cb4/plain.htm&node_id=90&show_children=false
http://help.sap.com/erp2005_ehp_07/helpdata/en/87/70b6531de6b64ce10000000a174cb4/content.htm
Then you will have to set the tolerance messages to error.
SAP Notes related:
2055131 - System allows to post Invoices for more than the quantity delivered and GR-Bsd IV is set
2004992 - MIRO/MIR7: System will not automatically propose "Amount" and "Quantity" after you have done GR 107
786810 - MM IV: Tolerance check when you enter invoices
Regards,
Carla