Receipt by receipt for everything... and I dislike using cash because then I have to track it even more closely, but that's the only way to get fresh local brown eggs.
As far as food taxes, I'm figuring $5 or $5.50 (I forget) in expenses, but I won't know what they actually were until I sit down and do my taxes in a week or two. I suppose if they are a lot higher then I may change that amount, but it's arbitrary anyway.
As far as the pest control it would either be a percentage (like the percentage of electricity bill), or all... the measure I use is whether I would have done it if I didn't have a business. I would have heat whether or not I had a B&B, so that one I go by percentage. I would not normally have hired the snow removal (just a one time thing when we had 8" and a full house), so to me that's 100% deductible.
=)
Kk..