If you don't want d3 to smooth the edges, you should remove the interpolation from the line generator.
https://jsfiddle.net/cexLbfnk/3/
var valueline2 = d3.svg.line()
.interpolate("basis") // this line needs to go
.x(function(d) {
return x(d.date);
})
.y(function(d) {
return y(d.JANSALES);
});