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 $85.41   9.527%   $93.547   $93.55   $93.55   $93.50  
  Purchase #2 $58.86   6.587%   $62.7371   $62.74   $62.75   $62.70  
  Purchase #3 $168.86   4.344%   $176.1953   $176.20   $176.20   $176.20  
  Purchase #4 $238.35   7.186%   $255.4778   $255.48   $255.50   $255.50  
  Purchase #5 $222.58   4.701%   $233.0435   $233.04   $233.05   $233.00  
  Purchase #6 $206.46   10.146%   $227.4074   $227.41   $227.40   $227.40  
  Purchase #7 $43.30   8.738%   $47.0836   $47.08   $47.10   $47.10  
  7 purchase totals = $1,023.82       $1,095.4917   $1,095.50   $1,095.55   $1,095.40