A way to make ALL rolls done by the GM in any way hidden. A "Toggle GM Screen" if you would.

listen... ive got 3 vampire spawn and 2 mezzoloths to roll stealth for and i dont want the players knowing about their existence at all if they succeed. and its REALLY suspicious annoying when the GM has to halt the entire game for 10 minutes to type out "/gmroll1d20+(mod)" 5 times while going character sheet to character sheet making sure to type out all of the right modifiers. please. for my own sanity and the sanity of every other GM out there... on the toolbar on the left. a big red button that toggles hidden rolls for whoever toggles it on or off. and no i dont want to hear "there's a community made macro for that" this is a very basic thing. GMs have screens. yet roll 20 doesnt. this is very frustrating and time consuming and i only get 4 hours of D&D in a week. dont make me waste any more time than i have to, i just want to roll the stealth checks really fast and get on with it. 

/talktomyself   Might be what you need.  I include a macro for /talktomyself in every game for myself as well as the player's.

to Vince SO CLOSE but not quite  i need something that does just the rolls and wont suddenly reveal everything once i turn it off. my entire party died and i couldnt even fudge rolls to save them 3 Nat 20s from vampires with guns all with near max damage rolls in a single round. wiped the whole team. not even my save the day at the last second with overpowered gear NPC i had run into the battlefield from the trees could help.  turns out a dangerous encounter turns deadly if your players dont go in with a battle plan and are down a wizard...

anything rolled while /talktomyself is on remains hidden to everyone else even after you toggle it off.  Note that these rolls will also be hidden in the chat archive.  About the only downside to /talktomyself; API scripts(pro perk) cannot be controlled from chat while /talktomyself is enabled.

hmmmmm... ill try it.

Not sure of the system nor sheet you are using but there is a method to toggle all rolls to whisper the GM but for your user case, I'm not sure it would be what you want. Interesting suggestion no matter what.

/talktomyself does not work when using API-scripts depending on the rolls. Doesn't concern the op, but thought I mention it.

Not only is there /talktomyself, but a large number of sheets have toggled whispering as an option. Also, assuming you're using 5E OGL, you could just set the NPC's sheet to toggle whisper, or always whisper, and then click whatever skill you need. Dexterity for Stealth check, for example.