### subticks in 2d plot

How would you control the subticks in a 2d plot?

```
var('x')
p=plot(5*sin(x/10)*sin(x),(x,0,20*pi))
p.show(ticks=[[0,5*pi,10*pi,15*pi,20*pi],5],tick_formatter="latex")
```

Gives the labelled ticks exactly where I would like them but I'd like to have unlabelled ticks at every pi value. In particular I'm looking at graphing
+-5sin(x/10) and having some students fill in the plot of the more complicated function