fully agreeing with "windowsill", let me also add that in "real life", this conversation takes on a bit of the "how many angels . . . . ", because in "real life" there are a number of things that prevent this activity --- first and foremost is that I NEVER trade with stop losses (before the yells and screams, I IDENTIFY the trend of the currency and ONLY trade in that direction, knowing that if i miss my profit taking point today, it will be there tomorrow and I maintain "scrupulous" money management techniques that do not place my margin in jeapordy, so dont try this at home unless you can tell what a trend IS and are willing to limit your exposure !)
If you choose to use a stop loss, you MUST be aware of the average daily pip movement for the currency youre trading. For instance, if one is trading GU, one would be rather dumb to set a stop loss less than 120 pips or so.
Retreating back towards the original question anyway, all of these things are within the power of the "house" to do, and while there will be moments that you see an "unusual" move or spike in the price, the dealer probably does it less than WE claim, and more than THEY claim ! (LOL)
I tend to feel a bit sorry for the "newbie" because, with 36 years trading experience and 7 years in forex, its rather simple at this point (for the most anyway -- not to say there are no "gotcha's" in my life) and understand that the only way forward is to learn and study and observe and then finally one day, as if G-D appeared on the streets, an immense HID light goes off, illuminating the sky, roadways and perhaps the Red Sea and you fall into your most comfortable chair, impaling yourself on your favorite pipe and see what and why things have been so difficult to grasp !
I refer to MY lightbulb as "reality trading" which is nothing more than cutting away the "hype", theory and silliness surrounding the markets and taking a good long look at its realities, which we all know is to MAKE MONEY AT ANY COST !!!
I would love to share knowledge freely, but after many a year I also know that until a newb learns what they DONT know, teaching you to be a sprinter, without teaching how to walk, becomes an enormously frustrating endevour !
Allow me to close with a simple truth --- if it is meant, you will find the way --- perhaps a tad "confucian" or "zen" in its outlook, but SO truthful in mine and probably better stated by the ever popular "when the student is ready, the teacher will appear !"
Proceed slowly but with determination and patience --- it takes at least a year and usually more to become "competetent" but you are trading against mere mortals (they just have MORE experience !)
ok, ive prattled on enough !
enjoy and trade well
mp
You can't expect an answer to this. You really have to look at Graphs and decide for yourself....How can anyone answering know what you are trading, what time frame you are in, how long you are holding, what your attitude towards risk is.....the list is endless.
If you can handle yourself, the rest is easy 
