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 $57.32   9.467%   $62.7465   $62.75   $62.75   $62.70  
  Purchase #2 $206.58   11.458%   $230.2499   $230.25   $230.25   $230.20  
  Purchase #3 $16.50   4.863%   $17.3024   $17.30   $17.30   $17.30  
  Purchase #4 $196.70   10.154%   $216.6729   $216.67   $216.65   $216.70  
  Purchase #5 $191.39   3.601%   $198.282   $198.28   $198.30   $198.30  
  Purchase #6 $249.25   10.867%   $276.336   $276.34   $276.35   $276.30  
  Purchase #7 $191.83   4.461%   $200.3875   $200.39   $200.40   $200.40  
  7 purchase totals = $1,109.57       $1,201.9772   $1,201.98   $1,202.00   $1,201.90