I got a note that an example of a filled in chart may be helpful, so here it is. I've filled this one in according to the directions I gave on the side, using the same amounts listed. Use whatever color pens inspire you, or you have on hand... or that match your decorating. I used highlighers because they were close by. I've also been known to write the actual dollar amount paid and the date each time with a notation on the left side of the chart. If you are using several charts at once, a different color, or set of colors, for each chart would work well too.
Please let me know how the charts are working for you, and where you have them posted. I'd love to hear from you, really!