Whenever you buy something in China, you should get a tax receipt (发票, fa piao). These receipts are used by the tax authorities to calculate and collect sales taxes, and also by government agencies to track their expenses. Consumers are strongly encouraged to get fa piao with all their purchases, but since that would prevent the vendor from not paying sales tax, the shops are making this as difficult as they possibly can. First of all, the fa piao is not integrated into the regular sales receipt, you are not given it automatically, you have to ask for it separately, sometimes not at the cashier, but at a special service counter. Even if you ask for a fa piao, you will sometimes be offered some handwritten papers without official stamps instead. Or you will be asked to come back later because they are out of forms at the moment, or the manager who has to do it has gone out for lunch (we have had all of this happen).

There is also a vibrant market for second-hand (or outright fake) fa piao, which can be used to draw money from expense accounts or tax returns. This seems to be risky business, at least if you overstep the unspoken limits that seem to socially accepted: six people in Guangdong have been sentenced to death for multi-billion dollar tax fraud in 2002. But use of this kind of fa piao in moderation (even though it must definitely constitute tax fraud) is terribly wide-spread and hard to avoid. Cissy's massage parlor gives her receipts for food, dated last year. Since I doubt that massages are tax deductible anyway, this is probably not a problem for us. But our monthly rent entitles us to a significant tax rebate. Of course, our land lord does not want to pay income tax on the rent and will not issue fa piao. There is not much we can do about that (and I doubt that other land lords would be any different), other than accepting the food and transportation receipts he gives us instead.

There are other grey zones. The girls at Walmart always write "food" on the receipt, no matter what I really bought. I'd look like a complete fool (no problem with that), and waste everyone's time if I tried to ask them to separate out the non-food items. My modus operandi now is to only get fa piao for purchases that include at least some food, and discard the totally-non-food receipts.

Having spent all my life in Germany and Japan, I am much more comfortable with following the law to the letter, rather than navigating unwritten grey areas of interpretation, but these are compromises that I think you have to work out in order to not lose your mind/cool/temper in China.