Yeah, the minimum raise is the last bet.
The big blind counts as a bet (which is why you can be the second person to act and be three-betting).
So with 5/10 blinds, the minimum a guy can raise is $10, making it $20 to go ($10 call, plus the $10 raise) for everybody up to the button ($15 to go for the SB, and $10 to go for the BB).
If the next guy wanted to three-bet that he has to put at least $10 more in, making it $30 to go for most of the people behind him.
Now, if the three-better said he was raising to $77 (a raise of $57) then if the next guy wanted to min-raise four-bet he'd have to put in $134 ($77 to cover the initial raises, +$57 to raise it the amount of the last raise).