Instead of budgeting $100 for clothes "in case you need it" why not budget a much smaller amount that gets put aside and accumulates. My clothing budget is $30 a month (it would be less if I could find cheaper work shoes). If I don't need anything, that money goes into a "roll over" savings account (I keep it separate from my EF, down payment and retirement savings accounts). Then, if in a few months I need to buy something, the money is available.

This works for me because my budget isn't changing all the time (this month I had $100 for clothes which I used but the month before that I used that $100 for savings, but next month I might need a new jacket which will be over $100, which category will I take the extra money from???). Clothing is always $30 a month.

I use this "roll over" account for multiple budget categories, mainly the ones that are used less frequently (like clothing or gifts) or bills that can vary a bit each month (like my cell phone). If this doesn't make sense, PM me and I'll try to explain it better.