I believe generic grade ceramics usually run 20% but 10% are available. When buying ceramics it is important to buy only X5R or X7R types. The ones labeled Z5U and Y5F are absolute garbage. They have horrible tempcos and only deliver about 1/5 of rated capacitance if used near their voltage rating.
I didn't forget. I don't recommend NPO/COG for general use because they are physically larger and much more expensive than X5R caps, also they are not available in larger sizes. They are justified in cases where caps have to be dead stable (like a precision timer or clock) but 99% of the time they are not required. Their claim to fame is zero tempco (stable over temp changes). X5R caps are pretty good for this, I think they stay within a 10 - 15% envelope over -40 to 150C range of temp. X5R and X7R are best for most uses. Z5U and Y5F really are junk that isn't adequate for ANY use.You forgot to mention that the best ceramic caps are marked NPO or COG. The others you mentioned have lower grade (X7R) and lowest grade (Z5U) dielectric materials.
I also find that the usual "crap" grade of disc ceramic caps tend to run high in value, especially if they have the "Z" tolerance code (which would make sense). These caps are usually used as bulk capacitance (decoupling circuits for example) and value is rarely an issue as long as it has a minimum value limit.