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 $225.61   5.381%   $237.7501   $237.75   $237.75   $237.80  
  Purchase #2 $239.49   8.421%   $259.6575   $259.66   $259.65   $259.70  
  Purchase #3 $162.37   8.444%   $176.0805   $176.08   $176.10   $176.10  
  Purchase #4 $119.30   5.228%   $125.537   $125.54   $125.55   $125.50  
  Purchase #5 $176.66   3.616%   $183.048   $183.05   $183.05   $183.00  
  Purchase #6 $76.25   6.508%   $81.2124   $81.21   $81.20   $81.20  
  Purchase #7 $58.82   6.806%   $62.8233   $62.82   $62.80   $62.80  
  7 purchase totals = $1,058.50       $1,126.1088   $1,126.11   $1,126.10   $1,126.10