I had found a way to quantize my markers to the snap value and have lost that shortcut. Can someone remind me how to do this?
Hi,
I’m out of Cubase at this moment, so I cannot test it.
If the default Q doesn’t work, then you had to make a Project Logical Preset and assign a custom Key Command.
This 
We can use a PLE setting markers to “round” by a number of ticks. If we want to round to 1/16ths, we should set the ticks to 120. Multiply by the unit we want, for example, if we want to quantize at beat, we can set this to 120 * 4=480, and if at bar, 480 * 4=1920. I’m talking about 4/4 here. 
Example (for rounding to bar):
Thank you. I browsed around the forum and was able to program a PLE that works for this purpose.