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 $91.28   3.176%   $94.1791   $94.18   $94.20   $94.20  
  Purchase #2 $158.36   3.774%   $164.3365   $164.34   $164.35   $164.30  
  Purchase #3 $175.99   9.797%   $193.2317   $193.23   $193.25   $193.20  
  Purchase #4 $244.83   10.499%   $270.5347   $270.53   $270.55   $270.50  
  Purchase #5 $208.93   6.515%   $222.5418   $222.54   $222.55   $222.50  
  Purchase #6 $141.81   4.817%   $148.641   $148.64   $148.65   $148.60  
  Purchase #7 $54.61   7.496%   $58.7036   $58.70   $58.70   $58.70  
  7 purchase totals = $1,075.81       $1,152.1684   $1,152.16   $1,152.25   $1,152.00