acknowledge divisability of $20 indicate mathematical results

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Need help designing a formula to discern the nearest increment of $20.00 then
show the results - one to indicate the result of the original subtraction
(e.g., $539.00 - $520.00 with $520.00 being the result) and the other column
with the remaining amount (e.g., $19.00).

This example would include three columns: 1) The original amount, 2) the
total result of $20.00 increments, and 3) what remains from the original
amount.

Is this possible? Thanx for any assistance.

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