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 $33.28   5.354%   $35.0618   $35.06   $35.05   $35.10  
  Purchase #2 $242.51   5.398%   $255.6007   $255.60   $255.60   $255.60  
  Purchase #3 $101.75   4.448%   $106.2758   $106.28   $106.30   $106.30  
  Purchase #4 $196.49   10.627%   $217.371   $217.37   $217.35   $217.40  
  Purchase #5 $182.75   6.374%   $194.3985   $194.40   $194.40   $194.40  
  Purchase #6 $132.94   4.523%   $138.9529   $138.95   $138.95   $139.00  
  Purchase #7 $146.41   9.768%   $160.7113   $160.71   $160.70   $160.70  
  7 purchase totals = $1,036.13       $1,108.3720   $1,108.37   $1,108.35   $1,108.50