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 $85.50   11.111%   $94.9999   $95.00   $95.00   $95.00  
  Purchase #2 $217.68   8.729%   $236.6813   $236.68   $236.70   $236.70  
  Purchase #3 $186.64   12.447%   $209.8711   $209.87   $209.85   $209.90  
  Purchase #4 $159.96   3.355%   $165.3267   $165.33   $165.35   $165.30  
  Purchase #5 $18.40   12.239%   $20.652   $20.65   $20.65   $20.70  
  Purchase #6 $248.38   6.819%   $265.317   $265.32   $265.30   $265.30  
  Purchase #7 $61.92   5.335%   $65.2234   $65.22   $65.20   $65.20  
  7 purchase totals = $978.48       $1,058.0714   $1,058.07   $1,058.05   $1,058.10