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 $83.75   13.510%   $95.0646   $95.06   $95.05   $95.10  
  Purchase #2 $194.73   5.609%   $205.6524   $205.65   $205.65   $205.70  
  Purchase #3 $216.38   12.806%   $244.0896   $244.09   $244.10   $244.10  
  Purchase #4 $220.78   10.830%   $244.6905   $244.69   $244.70   $244.70  
  Purchase #5 $178.62   7.133%   $191.361   $191.36   $191.35   $191.40  
  Purchase #6 $104.86   4.405%   $109.4791   $109.48   $109.50   $109.50  
  Purchase #7 $30.59   12.721%   $34.4814   $34.48   $34.50   $34.50  
  7 purchase totals = $1,029.71       $1,124.8186   $1,124.81   $1,124.85   $1,125.00