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 $31.27   8.564%   $33.948   $33.95   $33.95   $33.90  
  Purchase #2 $151.47   11.366%   $168.6861   $168.69   $168.70   $168.70  
  Purchase #3 $229.91   5.298%   $242.0906   $242.09   $242.10   $242.10  
  Purchase #4 $246.34   6.684%   $262.8054   $262.81   $262.80   $262.80  
  Purchase #5 $153.42   8.494%   $166.4515   $166.45   $166.45   $166.50  
  Purchase #6 $87.42   9.387%   $95.6261   $95.63   $95.65   $95.60  
  Purchase #7 $186.26   8.154%   $201.4476   $201.45   $201.45   $201.40  
  7 purchase totals = $1,086.09       $1,171.0553   $1,171.07   $1,171.10   $1,171.00