I'm not sure I know what you mean. If I understand you correctly, you have a tile-based game and want to move game objects in pixel steps, not tile steps.

I would suggest one of these two solutions:

1. Specify the position of objects with pixel precision. Simply move objects one pixel at a time (i.e. in one cycle of the game loop) in the appropriate direction. This will mean somewhat more effor in detecting collisions etc.

2. Use only each n'th cycle of the game loop for NPC and player movements, where n is the width/height of each tile in pixels. Use all remaining cycles to animate movements with pixel precision. For example, if you want to move an object to the right, move it one pixel in each game loop cycle. It will be exactly on the next tile after n cycles. Then, you can accept the next movement command from the player.

Hopefully that doesn't sound too confusing and I haven't misunderstood you...