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 $191.42   5.438%   $201.8294   $201.83   $201.85   $201.80  
  Purchase #2 $195.80   5.154%   $205.8915   $205.89   $205.90   $205.90  
  Purchase #3 $43.82   7.202%   $46.9759   $46.98   $47.00   $47.00  
  Purchase #4 $149.96   9.457%   $164.1417   $164.14   $164.15   $164.10  
  Purchase #5 $242.93   9.658%   $266.3922   $266.39   $266.40   $266.40  
  Purchase #6 $44.60   4.540%   $46.6248   $46.62   $46.60   $46.60  
  Purchase #7 $177.44   10.444%   $195.9718   $195.97   $195.95   $196.00  
  7 purchase totals = $1,045.97       $1,127.8273   $1,127.82   $1,127.85   $1,127.80