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 $58.64   5.258%   $61.7233   $61.72   $61.70   $61.70  
  Purchase #2 $218.59   8.479%   $237.1242   $237.12   $237.10   $237.10  
  Purchase #3 $118.85   12.337%   $133.5125   $133.51   $133.50   $133.50  
  Purchase #4 $204.59   5.814%   $216.4849   $216.48   $216.50   $216.50  
  Purchase #5 $233.85   5.591%   $246.9246   $246.92   $246.90   $246.90  
  Purchase #6 $215.58   6.662%   $229.9419   $229.94   $229.95   $229.90  
  Purchase #7 $222.93   3.387%   $230.4806   $230.48   $230.50   $230.50  
  7 purchase totals = $1,273.03       $1,356.1920   $1,356.17   $1,356.15   $1,356.10