Check duplicate values and combine cell values to form a single entry

Hi! Am using Windows 7 (SP1); MS Office 2013

I have duplicate Invoice numbers in column A and Taxable amount in column B and Tax in column C. I wish to avoid duplicate Invoice numbers, but the amounts in Taxable amount column values and Tax values should be added, so that I get a single entry of invoice number with added values of Taxable amount and Tax amount.

i.e.:
If the content or figure in column A are same
the simultaneous values in column B should be added and the total should be displayed on the last column of column E
and the simultaneous values in column C should be added and the total should be displayed on the last column of column F

Eg: Cell A1,A2,A3 are same
D3 should display "1"(Invoice No.)
Then B1,B2,B3 should be added and total should be displayed on E3
and C1,C2,C3 should be added and total should be displayed on F3

Please go through the attached excel sheet for more clarification

Thank you

You can do with a pivot table, see attached.