In this ruling, 5 Supreme Court Justices declared that the individual mandate penalty could ONLY be constitutional under Congress' authority to tax. Never mind that there is no type of tax specified in the Constitution to which this provision might actually conform.
Then these 5 Justices did something wholly illegal. They declared that, since the provision would only be constitutional as a tax, that it in fact is a tax.
Only Congress, NOT the Supreme Court, has the power to declare a tax. By declaring this provision a tax, when it did not originate in the House of Representatives as a tax, the Supreme Court has assumed the authority to lay a tax for itself, in direct contradiction of the Constitution they swore to uphold.