This is a property of an MRR raster, so in theory you could Convert your raster to an MRR with a restricted number of decimals and then Convert the MRR to ArcASCII. Unfortunately, we do not give you access to this property in the Convert operation.

You can do it manually with the Calculator operation. Use this formula -

floor(I1*pow(10,2) + 0.5)/pow(10,2)

In this formula "I1" is the input grid value and "2" is the number of decimal points you want to preserve in the data. The result is rounded to the nearest value so 3.2347 rounds to 3.23 and 3.2384 rounds to 3.24. You could output this straight to ArcASCII from the Calculator. Unfortunately, this doesn't quite work either because floating point numbers don't play nicely and when you output to ArcASCII you often find you don't have 3.23 but 3.299984 instead (or something). The results may vary depending on the magnitude of your elevation data so it is worth a try.