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 $62.48   8.622%   $67.867   $67.87   $67.85   $67.90  
  Purchase #2 $207.83   10.868%   $230.417   $230.42   $230.40   $230.40  
  Purchase #3 $75.39   13.445%   $85.5262   $85.53   $85.55   $85.50  
  Purchase #4 $113.48   11.673%   $126.7265   $126.73   $126.75   $126.70  
  Purchase #5 $250.80   6.466%   $267.0167   $267.02   $267.00   $267.00  
  Purchase #6 $191.44   9.778%   $210.159   $210.16   $210.15   $210.20  
  Purchase #7 $186.99   11.295%   $208.1105   $208.11   $208.10   $208.10  
  7 purchase totals = $1,088.41       $1,195.8229   $1,195.84   $1,195.80   $1,195.80