stamp duty tax

[joky]

Hello,
I want to be able to calculate the Stamp Duty tax In an easy way
Shown below is the current rates Using this formula

=IF(SUM(A2:D2)<=3000;"";IF(AND(SUM(A2:D2)>3001;SUM(A2:D2)<=3500);SUM(A2:D2)*1%;IF(AND(SUM(A2:D2)>3501;SUM(A2:D2)<=4000);SUM(A2:D2)*1.5%;IF(AND(SUM(A2:D2)>4001;SUM(A2:D2)<=4500);SUM(A2:D2)*2%;IF(AND(SUM(A2:D2)>4501;SUM(A2:D2)<=5000);SUM(A2:D2)*2.5%;IF(AND(SUM(A2:D2)>5001;SUM(A2:D2)<=5500);SUM(A2:D2)*3%;IF(AND(SUM(A2:D2)>5501;SUM(A2:D2)<=6000);SUM(A2:D2)*3.5%;IF(AND(SUM(A2:D2)>6001;SUM(A2:D2)<=6500);SUM(A2:D2)*4%;IF(AND(SUM(A2:D2)>6501;SUM(A2:D2)<=7000);SUM(A2:D2)*4.5%;IF(SUM(A2:D2)>7000;SUM(A2:D2)*5%))))))))))

How can I change the formula to UDF so as to easily use it.?
I have attached the expected results in this example
Thanks advanced for help