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 $59.41   5.260%   $62.535   $62.54   $62.55   $62.50  
  Purchase #2 $157.25   11.104%   $174.711   $174.71   $174.70   $174.70  
  Purchase #3 $105.32   4.799%   $110.3743   $110.37   $110.35   $110.40  
  Purchase #4 $219.78   10.169%   $242.1294   $242.13   $242.15   $242.10  
  Purchase #5 $111.90   4.368%   $116.7878   $116.79   $116.80   $116.80  
  Purchase #6 $57.56   4.609%   $60.2129   $60.21   $60.20   $60.20  
  Purchase #7 $104.57   13.174%   $118.3461   $118.35   $118.35   $118.30  
  7 purchase totals = $815.79       $885.0965   $885.10   $885.10   $885.00