Maybe something like this? It assumes the sprite's origin is on the left, that probably is a quick tweak. It's also untested so I'm not sure how well they distribute on the line. A second idea would be to first evenly distribute the sprites then jitter them around while preserving gaps to be >0
n : number of 10px sprites
FreeSpace = 100- 10*n
Gap:0
X:0
Repeat n times
---set gap to random(freespace)
--- subtract gap from freespace
--- add gap to X
--- create Sprite at (X,0)
--- add 10 to X