Identify the unfair aspect with respect to the sentence extracted from an online Terms of Service:
```
12.1 airbnb may , in its sole discretion , round up or round down amounts that are payable from or to guests or hosts to the nearest whole functional base unit in which the currency is denominated ( i.e. to the nearest dollar , euro or other supported currency ) ; for example , airbnb will round up an amount of $ 101.50 to $ 102.00 , and round down an amount of $ 101.49 to $ 101.00 . 

```
. OPTIONS: ['None' 'Unilateral change' 'Choice of law' 'Unilateral termination'
 'Limitation of liability' 'Content removal' 'Contract by using'
 'Arbitration' 'Jurisdiction'].