Everyone, effectively pays 15.3% of gross SS-covered wages up to $113,700 and 2.9% on income above that.
If you aren't self-employed, exactly (not "roughly") half of that (the so-called "employer's share") is not directly visible, while half of it is reflected in payroll deductions.
Balance is important here as the IRS watches these situations closely, but any decent accountant should help someone down this path.
I had prepared an example that showed you could actually pay less in FICA, while still being reasonable in the eyes of the IRS. Maybe not ideal to post it here though.
Here in the UK, the self employed pay less (9% vs 12%) in the equivalent tax (called National Insurance here) than the employed, with the tradeoff being that they can't claim various state unemployment benefits (for obvious reasons).
But I am annoyed my insurance costs are going up by quite a bit, but in the grand scheme of things I still pay very little.
Also, 92.35% of that profit is taxable, and as dragon writer said you stop paying FICA at $113,700 and then you play only 2.9% for Medicare.
Here are examples of self-employment tax at different levels of income:
$100,000 - $14,129.55 in taxes, an effective rate of 14.13%
$200,000 - $19,455.10 in taxes, an effective rate of 9.73%
$300,000 - $22,133.25 in taxes, an effective rate of 7.38%