This function should not be used except with the understanding that it is subject to errors at certain values (e.g., as @Will pointed out) due to the nature of floating-point. It's also not even vectorized!
26 Jul 2013
Round input to nearest multiple of arbitrary value.
Roundn is in the Mapping Toolbox which costs approximately $1,000.00 for a single user license. It is much simpler; however, it has fewer features and costs $1,000.00. The syntax for using roundn is reproduced from the Mathworks website to help anyone who reads this comment thread. Please let me know if a program with the simple syntax of Roundn would be of benefit to the Matlab Central Users Community.
roundn - Round to multiple of 10n
roundn(x,n) rounds each element of x to the nearest multiple of 10n. The variable n must be scalar, and integer-valued. For complex x, the imaginary and real parts are rounded independently. For n = 0, roundn gives the same result as round. That is, roundn(x,0) == round(x).