1. Edit an advanced tour.
    2. Choose the Price list tab.
    3. In the Options field there are two drop down lists for rounding selling prices.
    4. Change the way you wish to round the price in first drop down list

Disable rounding – no rounding at all
To higher – selling prices will get rounded to higher number you choose
To lower – selling prices will get rounded to lower number you choose
To closer – selling prices will get rounded to closer number you choose

  1. Change the number to which you want to round to

Whole number – selling prices will be rounded to a whole number
1 – 9 – selling prices will be rounded to the number you choose

  1. Click the Round button to round prices.
  2. Click OK to save changes.

Table that shows some rounding examples can be found
here.