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 $118.90   5.596%   $125.5536   $125.55   $125.55   $125.60  
  Purchase #2 $247.43   11.325%   $275.4514   $275.45   $275.45   $275.50  
  Purchase #3 $185.73   13.326%   $210.4804   $210.48   $210.50   $210.50  
  Purchase #4 $90.44   3.858%   $93.9292   $93.93   $93.95   $93.90  
  Purchase #5 $45.31   6.185%   $48.1124   $48.11   $48.10   $48.10  
  Purchase #6 $15.71   6.488%   $16.7293   $16.73   $16.75   $16.70  
  Purchase #7 $220.87   10.427%   $243.9001   $243.90   $243.90   $243.90  
  7 purchase totals = $924.39       $1,014.1564   $1,014.15   $1,014.20   $1,014.20