Help finding the right term - Behavioural Finance / Pricing jargon
A related concept you might be looking for could be &quot;mental accounting&quot;, first introduced by Richard Thaler.
According to mental accounting, people treat money as less fungible than it really is. Fungibility means that, all money is the same, regardless of any other factors, including intended use. However, people often budget money into mental accounts for expenses (e.g., saving for a home) or &quot;spare change&quot;.
In your example, the average person in NZ may have a 10$ mental account for &quot;spare change&quot;.
How optimal pricing works in behavioral theory is another discussion altogether though.