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 $72.55   4.855%   $76.0723   $76.07   $76.05   $76.10  
  Purchase #2 $118.89   5.548%   $125.486   $125.49   $125.50   $125.50  
  Purchase #3 $196.43   3.279%   $202.8709   $202.87   $202.85   $202.90  
  Purchase #4 $241.76   6.471%   $257.4043   $257.40   $257.40   $257.40  
  Purchase #5 $116.98   5.237%   $123.1062   $123.11   $123.10   $123.10  
  Purchase #6 $122.96   8.524%   $133.4411   $133.44   $133.45   $133.40  
  Purchase #7 $144.59   4.457%   $151.0344   $151.03   $151.05   $151.00  
  7 purchase totals = $1,014.16       $1,069.4152   $1,069.41   $1,069.40   $1,069.40