I'm setting up a domain for a currency type. I'm not sure what size to make
it. Each field would be in the hundreds of dollars typically, almost never
over a $1000.

However, aggregate calculations on those numbers could be in the millions
after some time. Does the size of the field affect the aggregate output?

I think DECIMAL(6,2) would easily store what is necessary. Also why not
just make it way too big so as not to worry about it? Are there significant
performance issues with making the field way bigger then I need?

Thanks,

Anthony