Here is how to create Jenks breaks classification for maps with ggplot2 with class labels that show only the top number in the class.

classes <- classIntervals(joined$Value, n = 9, style = "fisher")

joined <- joined %>% mutate(percent_class = cut(joined$Value, breaks=classes$brks, include.lowest = T,
labels=scales::comma(classes$brks[2:length(classes$brks)]),0) )