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 $88.78   7.629%   $95.553   $95.55   $95.55   $95.60  
  Purchase #2 $190.38   9.560%   $208.5803   $208.58   $208.60   $208.60  
  Purchase #3 $222.58   5.384%   $234.5637   $234.56   $234.55   $234.60  
  Purchase #4 $181.44   13.138%   $205.2776   $205.28   $205.30   $205.30  
  Purchase #5 $200.71   3.397%   $207.5281   $207.53   $207.55   $207.50  
  Purchase #6 $33.84   3.707%   $35.0944   $35.09   $35.10   $35.10  
  Purchase #7 $207.40   4.358%   $216.4385   $216.44   $216.45   $216.40  
  7 purchase totals = $1,125.13       $1,203.0356   $1,203.03   $1,203.10   $1,203.10