If you're not happy with what R puts on the axes of your plot (tickmarks, labels etc), plot with "axes=F", then add custom axes with the "axis()" function.
Example:
budget <- 360 plotmax <- budget+30 w1 <- 134 w2 <- 70 w3 <- 70 w4 <- 60 weeks <- matrix(c(w1,w2,w3,w4)) par(las=1) # we want all labels to be horizontal # draw the plot without axes: barplot(weeks, beside=F, ylim=c(0,plotmax),xlim=c(0,2),axes=F) # draw one custom axis, in grey, that sets tickmarks at 10,20,30 etc axis(2,at=seq(0,plotmax,by=10),col="grey",labels=F) # draw another axis on top of it that draws black tickmarks at 50,100 etc # and that labels these numbers axis(2,at=seq(0,plotmax,by=50),col="black")