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 $202.58   5.761%   $214.2506   $214.25   $214.25   $214.30  
  Purchase #2 $43.36   5.545%   $45.7643   $45.76   $45.75   $45.80  
  Purchase #3 $139.98   8.207%   $151.4682   $151.47   $151.45   $151.50  
  Purchase #4 $116.53   11.248%   $129.6373   $129.64   $129.65   $129.60  
  Purchase #5 $207.28   8.336%   $224.5589   $224.56   $224.55   $224.60  
  Purchase #6 $51.39   8.398%   $55.7057   $55.71   $55.70   $55.70  
  Purchase #7 $214.81   9.347%   $234.8883   $234.89   $234.90   $234.90  
  7 purchase totals = $975.93       $1,056.2733   $1,056.28   $1,056.25   $1,056.40