Problem Statement  
Most of the time when rounding a given number, it is customary to round to some multiple of a power of 10. However, there is no reason why we cannot use another multiple to do our rounding to. For example, you could round to the nearest multiple of 7, or the nearest multiple of 3. Given an int n and an int b, round n to the nearest value which is a multiple of b. If n is exactly halfway between two multiples of b, return the larger value.  
Definition  
 
Constraints  
  n will be between 1 and 1000000, inclusive.  
  b will be between 2 and 500, inclusive.  
Examples  
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