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 $162.26   7.637%   $174.6518   $174.65   $174.65   $174.70  
  Purchase #2 $184.55   12.587%   $207.7793   $207.78   $207.80   $207.80  
  Purchase #3 $239.51   10.401%   $264.4214   $264.42   $264.40   $264.40  
  Purchase #4 $118.59   7.428%   $127.3989   $127.40   $127.40   $127.40  
  Purchase #5 $95.95   13.745%   $109.1383   $109.14   $109.15   $109.10  
  Purchase #6 $186.84   11.161%   $207.6932   $207.69   $207.70   $207.70  
  Purchase #7 $67.83   4.274%   $70.7291   $70.73   $70.75   $70.70  
  7 purchase totals = $1,055.53       $1,161.8120   $1,161.81   $1,161.85   $1,161.80