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 $33.49   6.387%   $35.629   $35.63   $35.65   $35.60  
  Purchase #2 $207.76   4.164%   $216.4111   $216.41   $216.40   $216.40  
  Purchase #3 $170.42   11.220%   $189.5411   $189.54   $189.55   $189.50  
  Purchase #4 $231.53   12.634%   $260.7815   $260.78   $260.80   $260.80  
  Purchase #5 $44.54   3.148%   $45.9421   $45.94   $45.95   $45.90  
  Purchase #6 $242.78   6.853%   $259.4177   $259.42   $259.40   $259.40  
  Purchase #7 $102.66   3.745%   $106.5046   $106.50   $106.50   $106.50  
  7 purchase totals = $1,033.18       $1,114.2271   $1,114.22   $1,114.25   $1,114.10