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 $114.88   8.796%   $124.9848   $124.98   $125.00   $125.00  
  Purchase #2 $156.32   3.439%   $161.6958   $161.70   $161.70   $161.70  
  Purchase #3 $171.84   7.330%   $184.4359   $184.44   $184.45   $184.40  
  Purchase #4 $59.91   6.655%   $63.897   $63.90   $63.90   $63.90  
  Purchase #5 $66.41   5.346%   $69.9603   $69.96   $69.95   $70.00  
  Purchase #6 $242.43   12.492%   $272.7144   $272.71   $272.70   $272.70  
  Purchase #7 $218.40   7.719%   $235.2583   $235.26   $235.25   $235.30  
  7 purchase totals = $1,030.19       $1,112.9465   $1,112.95   $1,112.95   $1,113.00