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 $85.51   11.121%   $95.0196   $95.02   $95.00   $95.00  
  Purchase #2 $163.30   12.766%   $184.1469   $184.15   $184.15   $184.10  
  Purchase #3 $87.38   7.616%   $94.0349   $94.03   $94.05   $94.00  
  Purchase #4 $149.58   10.178%   $164.8043   $164.80   $164.80   $164.80  
  Purchase #5 $224.87   10.484%   $248.4454   $248.45   $248.45   $248.40  
  Purchase #6 $181.56   4.843%   $190.353   $190.35   $190.35   $190.40  
  Purchase #7 $160.87   9.682%   $176.4454   $176.45   $176.45   $176.40  
  7 purchase totals = $1,053.07       $1,153.2495   $1,153.25   $1,153.25   $1,153.10