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 $86.96   8.475%   $94.3299   $94.33   $94.35   $94.30  
  Purchase #2 $200.25   11.140%   $222.5579   $222.56   $222.55   $222.60  
  Purchase #3 $65.31   10.515%   $72.1773   $72.18   $72.20   $72.20  
  Purchase #4 $107.29   8.651%   $116.5717   $116.57   $116.55   $116.60  
  Purchase #5 $186.40   11.574%   $207.9739   $207.97   $207.95   $208.00  
  Purchase #6 $217.82   11.379%   $242.6057   $242.61   $242.60   $242.60  
  Purchase #7 $215.67   13.820%   $245.4756   $245.48   $245.50   $245.50  
  7 purchase totals = $1,079.70       $1,201.6920   $1,201.70   $1,201.70   $1,201.80