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 $119.58   5.140%   $125.7264   $125.73   $125.75   $125.70  
  Purchase #2 $120.60   12.771%   $136.0018   $136.00   $136.00   $136.00  
  Purchase #3 $73.63   5.874%   $77.955   $77.96   $77.95   $78.00  
  Purchase #4 $145.86   6.410%   $155.2096   $155.21   $155.20   $155.20  
  Purchase #5 $164.39   4.581%   $171.9207   $171.92   $171.90   $171.90  
  Purchase #6 $179.46   4.146%   $186.9004   $186.90   $186.90   $186.90  
  Purchase #7 $241.56   7.574%   $259.8558   $259.86   $259.85   $259.90  
  7 purchase totals = $1,045.08       $1,113.5697   $1,113.58   $1,113.55   $1,113.60