Your mention of "The meaning of Liff" sent me back to the book to find his version of "chump change":
chump change n (chiefly N Am inf ) an insignificant or insultingly small amount of money
Kibblesworth (n.) The footling amount of money by which the price of a given article is less than a sensible number, in the hope that at least one idiot will think it cheap. For instance, the kibblesworth on a pair of shoes priced at £19.99 is 1p.
(Note 1: there is in fact a very rational reason for the owner of a shop to price an item at £19.99 rather than £20
Note 2: publishing date 1990 - shoes cost more now!)