Picture posting is enabled for all :)
I like the saying"sunshine is the best disinfectant". If everyone can easily see what is happening it is very difficult to get away with any cheating. Earlier, someone suggested making copies. This is an excellent idea. You would do well to implement it from here in. Receipt held by treasurer, copy placed in committee files, open to all.
I suppose most people don't care if the treasurer loses receipts or the chairman fiddles a bit