What should my friend do now that she has to provide her payslips after lying about her current salary at a job interview?

Though lying is not encouraged, most people will treat her case as rounding up only, which is rather common, esp since the gap isn’t that big a difference. I’m sure she’ll be fine and good luck with her new job!

Like everyone said, the rounding up is not much of a big deal as the difference is relatively small.

However, the bigger concern here is, the fact that we are all willing to provide a copy of a confidential document such as a payslip.
Sharing payslips to hiring teams has been a widespread practice, but that doesn't necessarily make it right.

You may politely refuse due to code of conduct and confidentiality concerns. You may even challenge the hiring team if they normally allow their employees sharing their payslip (am almost certain they would not want either). So rather than payslip, provide other means of proof like tax computation or salary credit bank statement. The hiring manager may even add integrity points to you for doing that :)

$2940 and $3000 is only $60.

Most employers are able to understand this small difference due to rounding-up.

For a second, I thought "your friend" exaggerated in hundreds. Meh. $60 is fine.

Rest assured that the employer is most keen about her abilities and skillset, not so much about her last pay.

This aside, what else can she do besides providing the payslip? Not much choice she has, right? So go ahead and provide the payslip. Don't have to make excuses or apologises, its just a small round-up.

Enjoy the new job!

Just provide the latest 2 months payslip lo.