replace some elements to zero if they are not NaN

I have a matrix

A=[2 3 NaN NaN 3 NaN NaN 9 9 9;
  3 4 NaN NaN 3 NaN NaN 9 5 8; 
  1 2 NaN NaN 4 NaN NaN 8 7 9]

I want to replace 30% of non zero elements in each row to 0.. for example, 30% of non-zero elements is 2.I want to replace each row with 2 zeros

A=[0 3 NaN NaN 3 NaN NaN 9 0 9;
    3 4 NaN NaN 0 NaN NaN 9 0 8; 
    1 0 NaN NaN 4 NaN NaN 8 0 9]

how can I do this? I have done some but for that case no Nan is available in matrix but in this case I want that Nan remains and rest is replaced. Please guide.

[jonas]

30% of 6 is not 2. Do you round off any decimals? Also, do you want to select those two numbers randomly?

[Jan]

If no NaNs are available, you want to keep the NaNs and the rest is replaced? This sounds confused. What exactly are 30%, if the number of columns is not a multiple of 10?