Hi, just to put the Scotland/UK now NZ spin on this, the general term is 'on tick' and usually refers to paying later or hire purchase, i.e. not paying for the good outright. Buying things from a catalogue, clothes etc, can be referred to as 'on tick'. Another use is 'on the slate' usually drinks in a bar but can also mean on tick. I have to admit to not hearing the 'the' used in the term 'on the tick', I think it's called 'on tick'.
Clear as mud.. (Unfortunately any google takes you into the world of fleas...)
Regards,
Andy