Let's do some math ..  Rounding examples of 7 random hypothetical purchases:
  Case Tag  
Price  
Sales  
Tax %  
Raw Total  
Incl. Sales Tax  
Rounded  
to Penny  
Rounded  
to Nickel  
Rounded  
to Dime  
  Purchase #1 $108.38   5.330%   $114.1567   $114.16   $114.15   $114.20  
  Purchase #2 $184.35   5.676%   $194.8137   $194.81   $194.80   $194.80  
  Purchase #3 $188.34   8.830%   $204.9704   $204.97   $204.95   $205.00  
  Purchase #4 $92.26   5.286%   $97.1369   $97.14   $97.15   $97.10  
  Purchase #5 $198.45   4.867%   $208.1086   $208.11   $208.10   $208.10  
  Purchase #6 $187.45   7.627%   $201.7468   $201.75   $201.75   $201.70  
  Purchase #7 $50.67   6.199%   $53.811   $53.81   $53.80   $53.80  
  7 purchase totals = $1,009.90       $1,074.7441   $1,074.75   $1,074.70   $1,074.70