Normally dice rolls are not needed for routine actions like tossing something aside. But if a player accidentally makes a roll when one is not needed, you should feel free to interpret creatively.

On the player side: Try making pre-emptive rolls for stuff like this and see if you can confuse your GM enough to get some sort of advantage out of it.

Transcript

GM: Inside, more troopers arrive.
Colonel Dyer: 'Allo 'allo 'allo... What's all this, then?
Han: I blast him!
GM: Your blaster's holstered. And you're holding an explosive charge, in both hands.
Han: I throw it away. 20!
GM: Um.
[SFX]: krunch! {the charge hits Dyer; he falls backwards over a railing}
Colonel Dyer: Aaaargh!
Chewbacca: He fell over a railing?
GM: Yes.
Chewbacca: There was a railing?
Leia: I see now why they don't usually bother.