r ggplot scale_fill_gradient breaks code example

Example: r ggplot scale_fill_gradient breaks

+ scale_fill_gradient(high = "springgreen4", low= "grey90", name="Sum", 
          labels = c("5,000,000", "4,000,000", "3,000,000", "2,000,000", "1,000,000"),
           breaks = c(5000000, 4000000, 3000000, 2000000, 1000000))