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 $114.29   10.200%   $125.9476   $125.95   $125.95   $125.90  
  Purchase #2 $207.50   11.828%   $232.0431   $232.04   $232.05   $232.00  
  Purchase #3 $240.71   11.467%   $268.3122   $268.31   $268.30   $268.30  
  Purchase #4 $203.29   11.688%   $227.0505   $227.05   $227.05   $227.10  
  Purchase #5 $18.41   13.661%   $20.925   $20.93   $20.95   $20.90  
  Purchase #6 $146.88   10.342%   $162.0703   $162.07   $162.05   $162.10  
  Purchase #7 $45.71   9.370%   $49.993   $49.99   $50.00   $50.00  
  7 purchase totals = $976.79       $1,086.3417   $1,086.34   $1,086.35   $1,086.30