How to improve plotting figure when averaging within bins

I am trying to take the mean of bins that I assign and have done so in the following way:

binEdge = linspace(min(a), max(a), 5);
[n,bin] = histc(a, binEdge); 
A = accumarray(bin(:),P1,[],@mean)
figure
plot(binEdge, A);
xticks([0, 0.02, 0.04, 0.06, 0.08, 0.1);

However the plot I am getting doesn't show a single value for each bin i.e. like a stepwise function would look. It's all linear and I'm wondering how to change that. Thanks