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 $116.68   7.434%   $125.354   $125.35   $125.35   $125.40  
  Purchase #2 $62.34   10.679%   $68.9973   $69.00   $69.00   $69.00  
  Purchase #3 $116.85   4.559%   $122.1772   $122.18   $122.20   $122.20  
  Purchase #4 $177.73   6.842%   $189.8903   $189.89   $189.90   $189.90  
  Purchase #5 $170.43   12.212%   $191.2429   $191.24   $191.25   $191.20  
  Purchase #6 $108.38   5.734%   $114.5945   $114.59   $114.60   $114.60  
  Purchase #7 $192.48   11.398%   $214.4189   $214.42   $214.40   $214.40  
  7 purchase totals = $944.89       $1,026.6751   $1,026.67   $1,026.70   $1,026.70