I agree with GilSwillBasementBrews, but make sure to do calculation using the warmest temp your beer has been at since fermentation was complete. There will be a noticeable difference in amounts of PS needed from 60 to say 70 degrees. Here is a link to Norther Brewers calculator http://www.northernbrewer.com/priming-sugar-calculator/
Whiskey's too rough, champagne costs too much, vodka puts my mouth in gear
This little refrain should help me explain as a matter of fact I like beer - Tom T Hall
I agree with Thakaz; just use table sugar. As stated earlier, however, note the difference in calculation. You shouldn't notice much of a difference, but it may take just a little longer as sucrose is a sugar molecule that needs to first be broken down into fructose and glucose before it can be fermented by the remaining yeast. Dextrose is pretty much the same thing as glucose and is 100 percent fermentable while sucrose must first have the molecular chains broken down by the yeast. Either way you'll be fine provided you measure the correct amount.
If you use brown sugar or demerara (raw cane) sugar,use the talbe sugar amount in the priming calculators. But they won't do much more than add a little to the flavor complexity,since not much is being used to prime.