Show data with values 1% of each other

Hello,

i have the following data set

Contractor Invoice #  Amount

A                    1           $100

A                    2           $101

A                    3            $150

A                    4            $200

B                    1           $200

B                    2              $201

how can I show for each contractor invoices or amounts where the  values that are within 1% of each other? in this case, invoice 1 and 2 for contractor A are 1% of each other and 1 and 2 for contractor B

Thank you!

Marina