I guess the best answer is a solid *maybe*. You are looking at a proxy for the market. What the real market is, unfortunately, difficult to see, especially as a retail trader. Banks will trade bank-to-bank on the Interbank market, and trades won't post for all to see on a centralized exchange, as you may be accustomed to seeing.
So, in the best case, you might see many of the large banks bid and ask prices if you are trading directly on the Interbank market. Otherwise, the closest you may get is an ECN. But even so, and ECN is just a localized market of traders putting up bids and offers. In some or many cases, your bid or offer will get sent to the Interbank if the larger market crosses it.
It's probably best to ignore the true spread of the market for figuring your trading costs. As a retail trader, you might get your limit filled on an ECN, but that will depend on liquidity, your size, and the near term move of the market. I consider it a bonus to get a fill this way. The norm is to expect to pay up and enter across the book: buy the offer or sell into the bid.
You may dispute this, and it's one person's opinion only, but over many, many trades, I've found that either the market will need to move into my limit or I pay across that spread to change my position. Either way, I pay it as a cost of doing business.
The real question is "How far was that bid that I hit from the "real" bids in the Interbank market?" That is of course, hard to answer, but it's clearly less than the full spread. I'd compare the spread you are referring to with some other brokers as well as an ECN. Let's choose OandA, as an example because they record and make available their historical spreads. During peak market times, the spread looks to be about 2.5 to 3.0. An ECN like Interactive Brokers may be 2.0. So, you could say roughly that you are "padded" by about 1.5 pips on either side (I'm assuming that the broker makes their spreads from the center of the market, although you'll often see that this can be biased to a bullish or bearish slant if you watch multiple feeds.)
Roughly speaking then, you would be paying an extra 1.5 pips on each side of the transaction. So, I'd answer your original question by saying "about 3 pips."
But you aren't actually being charged an additional fee. All of this discussion is about costs that are built into the transaction with these types of dealing desk brokers. If you make a gross profit on the result of your trade, it's yours to keep. Gross profit = net profit and gross loss = net loss. There will not be a separate commission charged.
