Final answer:
The sentence "Grandma is coming over today, so I need you to clean your room" is a compound-complex sentence.
Step-by-step explanation:
The sentence "Grandma is coming over today, so I need you to clean your room" is a compound-complex sentence. It contains two main clauses (independent clauses) and one subordinate clause. The main clauses are "Grandma is coming over today" and "I need you to clean your room", while the subordinate clause is "so". The use of both main and subordinate clauses makes this sentence a compound-complex sentence.