29 knuts = 1 sickle
17 sickles = 1 galleon
493 knuts = 1 galleon

1 knut = £.01 or $.02
£.01 or $.02 in 1882 = £.28 or $.45 now

1 sickle = £.29 or $.59
£.29 or $.59 in 1882 = £8.25 or $13.16 now

1 galleon = £5 or $10.07
£5 or $10.07 in 1882 = £140.75 or $224.60 now

10 galleons = £50 or $100.70
£50 or $100.70 in 1882 = £1408.33 or $2246.01 now

Money was a great deal of what made someone belong to a certain class, although it was not everything. Pay levels one and two were enough that they could launch one into the upper class; everything else did not, and some jobs (such as prostitute) automatically thrust someone into the lower class no matter how much or little they made.

It was very difficult to work ones way into the upper class, and when it was done it was usually done through owning a large business -- something much larger than a simple shop -- and the problem with entering the upper class through business was that a bad year could return you to the middle class or even destroy you completely and leave you in the lower class.

For the most part, it was birth or marriage that determined class, and class was quickest lost through reputation. Although a man would not remain long in the upper class if he were a common laborer, and even a middle class woman would fall to the lower class for prostitution, most work did not change ones class.

It was much easier to move down the social ladder than up (a baby out of wedlock, for example, could ruin a girl's reputation and thrust her into the lower class). The easiest way to move up in class was marriage, and even that option was usually only available to women because in most cases a woman took on her husband's social class.

Documentation written by Emily and Kayte exclusively for Charming.
Many thanks to the following sources:
Google
Harry Potter Lexicon: Wizarding World currency Converter
Harry Potter Wiki: Wizarding Currency
The Inflation Calculator