** Using WeBWorK **

Yes it can, but with limitations. Set snapSizeX to what you need. It must be greater than zero. In fact technically it must be greater than JSXGraphs JXG.Math.eps which is 1e-5 (if I recall correctly). There are some issues with rounding in some cases though, and with small snap sizes it can be hard to place the points at infinity on the number line.  The arrow keys on the keyboard may be necessary in some cases to accurately place points. There are some improvements in https://github.com/openwebwork/pg/pull/1157 that make things a little better for the rounding issues and placing points at the edge of the board. In any case, values such as snapSizeX = 1/2, snapSizeX = 1/5, or snapSizeX = 1/10 should work fine.