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 $86.49   9.860%   $95.0179   $95.02   $95.00   $95.00  
  Purchase #2 $249.27   7.673%   $268.3965   $268.40   $268.40   $268.40  
  Purchase #3 $14.50   4.659%   $15.1756   $15.18   $15.20   $15.20  
  Purchase #4 $139.88   9.207%   $152.7588   $152.76   $152.75   $152.80  
  Purchase #5 $232.34   9.624%   $254.7004   $254.70   $254.70   $254.70  
  Purchase #6 $132.55   7.671%   $142.7179   $142.72   $142.70   $142.70  
  Purchase #7 $220.89   6.857%   $236.0364   $236.04   $236.05   $236.00  
  7 purchase totals = $1,075.92       $1,164.8035   $1,164.82   $1,164.80   $1,164.80