If it were me, and that was all I had to go on, I'd take the amount and work out the likely combinations of goods that you might buy with that amount, then use other purchases where the store was likely to be selling one thing to alter the probability assigned to various purchase combinations. You could also weight it by buying frequency, the likelihood of particular purchasing habits in their demographic - things like that.

Maybe you wouldn't be able to tell precisely what someone bought, but I imagine you could get a reasonable idea.

Not that I don't imagine - the article and rosser say as much - that they have other sources of info.