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 $85.41   11.236%   $95.0067   $95.01   $95.00   $95.00  
  Purchase #2 $23.31   3.265%   $24.0711   $24.07   $24.05   $24.10  
  Purchase #3 $219.65   12.446%   $246.9876   $246.99   $247.00   $247.00  
  Purchase #4 $229.33   3.721%   $237.8634   $237.86   $237.85   $237.90  
  Purchase #5 $222.54   12.429%   $250.1995   $250.20   $250.20   $250.20  
  Purchase #6 $61.46   13.821%   $69.9544   $69.95   $69.95   $70.00  
  Purchase #7 $164.49   4.387%   $171.7062   $171.71   $171.70   $171.70  
  7 purchase totals = $1,006.19       $1,095.7889   $1,095.79   $1,095.75   $1,095.90