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 $54.59   6.300%   $58.0292   $58.03   $58.05   $58.00  
  Purchase #2 $124.38   12.477%   $139.8989   $139.90   $139.90   $139.90  
  Purchase #3 $159.67   13.831%   $181.754   $181.75   $181.75   $181.80  
  Purchase #4 $72.68   4.357%   $75.8467   $75.85   $75.85   $75.80  
  Purchase #5 $205.62   4.380%   $214.6262   $214.63   $214.65   $214.60  
  Purchase #6 $202.61   9.770%   $222.405   $222.41   $222.40   $222.40  
  Purchase #7 $190.96   6.143%   $202.6907   $202.69   $202.70   $202.70  
  7 purchase totals = $1,010.51       $1,095.2507   $1,095.26   $1,095.30   $1,095.20