There will be Rollover at 00:00 in GMT+2(GMT+3 in DST) for Forex pairs.
Although, there is no Rollover on Saturdays and Sundays when the markets are closed, banks still calculate interest on any position held over the weekend.
And XM applies a 3-day rollover on Wednesdays.
Meaning that on Wednesdays, the swap point is tripled.
How to calculate the swaps(rollover charge)
You can simply refer to the swap points in MT4.
Interest(swap) is paid on the borrowed currency and earned on the purchased currency.
For calculation or Swap, Profit/Loss and others numbers, you can use XM’s free online calculator in the Official Website.
Alternatively you can open a Demo account to see how these numbers are calculated.