Chodo'd comes from the Japanese 'Chodo' (丁度 or ちょうど) meaning 'just, right or exactly'
If you give the correct change to clerks in Japanese stores they
will usually respond by saying 'はい、丁度です' (
hai, chodo desu) meaning 'Yes, thats exact/right/correct'
Giving exact change is extremely
popular in Japan due to the annual Chodo Kyousou (丁度競争 or ちょうどきょうそう)or 'Exact Change Competition'.
People carry around
small books (which, upon completion are replaced at
JP post offices) which are stamped by officially participating stores, transportation companies, etc. in the hope of being crowned '丁度の王' (ちょどうのおう or chodo no ou) 'King of the Chodo'.
Another factor in its popularity is the populations preference of using coins, over the Nihon Ginko (Japananese Bank) notes as by doing so they are
literally 'saving face(s)'.
The action and term, has found its popularity spread amongst English speaking residents of Japan in recent years and jubilant cries of 'Chodo'd' can be heard throughout the many combini's of Nihon .