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 $53.75   9.853%   $59.046   $59.05   $59.05   $59.00  
  Purchase #2 $244.93   7.336%   $262.8981   $262.90   $262.90   $262.90  
  Purchase #3 $99.45   6.158%   $105.5741   $105.57   $105.55   $105.60  
  Purchase #4 $173.47   4.357%   $181.0281   $181.03   $181.05   $181.00  
  Purchase #5 $200.78   3.193%   $207.1909   $207.19   $207.20   $207.20  
  Purchase #6 $195.78   6.376%   $208.2629   $208.26   $208.25   $208.30  
  Purchase #7 $158.79   13.138%   $179.6518   $179.65   $179.65   $179.70  
  7 purchase totals = $1,126.95       $1,203.6519   $1,203.65   $1,203.65   $1,203.70