Some of the advice above is good and some is completely wrong.
You can roll the entire amount into another Roth without paying any penalty as long as you do it within 60 days. However, the catch is that you need to also roll over the amount of the 20% that they withheld with additional funds. In other words, if your IRA was 10,000, they withheld 2k and gave you 8k. You need to rollover the 8k and another 2k from your savings or some type of loan for a total rollover of 10k. When you file your tax return, the 2k they withheld is additional taxes paid and your refund will be 2k larger than it would have been.
If you don’t rollover the 2k, it will be considered a distribution and you will owe taxes and penalties on it. However, since the IRS already has the money, you will get a portion of the 2k back as a tax refund.
Here’s an example from the IRS web site:
https://www.irs.gov/retirement-plans...-distributions