A common misconception is that your miner software tells the mining pool what your hashrate is. What actually happens is a calculation based on the shares you submit and the difficulty of those shares. We can work out that for your submitted shares at the difficulty target assigned to you it would roughly take XXXhs.
As you process the jobs sent to you, you can be lucky or unlucky meaning you will find the share quicker or slower than expected. This causes the "saw blade" type graph and is nothing to worry about. Averaged out over a period of time we can calculate that you have roughly 6 KH/s (using the graph above).
If the pool is accepting your shares you will be getting paid as intended by the coin developers.
Edited by Snider