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 $119.36   5.333%   $125.7255   $125.73   $125.75   $125.70  
  Purchase #2 $117.87   6.545%   $125.5846   $125.58   $125.60   $125.60  
  Purchase #3 $236.46   4.853%   $247.9354   $247.94   $247.95   $247.90  
  Purchase #4 $158.85   5.572%   $167.7011   $167.70   $167.70   $167.70  
  Purchase #5 $210.82   3.854%   $218.945   $218.95   $218.95   $218.90  
  Purchase #6 $199.31   8.468%   $216.1876   $216.19   $216.20   $216.20  
  Purchase #7 $28.48   9.316%   $31.1332   $31.13   $31.15   $31.10  
  7 purchase totals = $1,071.15       $1,133.2124   $1,133.22   $1,133.30   $1,133.10