break Link in excel and keep data

I would like to know if any one would know how if possible to break a link after it has filled a sheet with data.
I have a spread sheet that we enter monthly maintinence costs in and the customer wants a quarterly report. I want to be able to have a sheet for each month and then have a another one that is a total of the three months, I use a formula that adds the three months and inputs it in the quarterly report, but then the quarterly report is linked to the three months. I want to break this link with out loosing the data so I can send just the quarterly report.