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 $214.65   7.145%   $229.9867   $229.99   $230.00   $230.00  
  Purchase #2 $240.81   5.702%   $254.541   $254.54   $254.55   $254.50  
  Purchase #3 $49.95   5.280%   $52.5874   $52.59   $52.60   $52.60  
  Purchase #4 $164.34   6.864%   $175.6203   $175.62   $175.60   $175.60  
  Purchase #5 $237.99   11.558%   $265.4969   $265.50   $265.50   $265.50  
  Purchase #6 $46.80   4.106%   $48.7216   $48.72   $48.70   $48.70  
  Purchase #7 $223.81   5.800%   $236.791   $236.79   $236.80   $236.80  
  7 purchase totals = $1,178.35       $1,263.7449   $1,263.75   $1,263.75   $1,263.70