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 $41.40   4.864%   $43.4137   $43.41   $43.40   $43.40  
  Purchase #2 $218.53   13.118%   $247.1968   $247.20   $247.20   $247.20  
  Purchase #3 $56.82   3.499%   $58.8081   $58.81   $58.80   $58.80  
  Purchase #4 $20.79   7.542%   $22.358   $22.36   $22.35   $22.40  
  Purchase #5 $87.55   10.470%   $96.7165   $96.72   $96.70   $96.70  
  Purchase #6 $72.73   13.411%   $82.4838   $82.48   $82.50   $82.50  
  Purchase #7 $193.63   8.161%   $209.4321   $209.43   $209.45   $209.40  
  7 purchase totals = $691.45       $760.4090   $760.41   $760.40   $760.40