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 $58.38   8.764%   $63.4964   $63.50   $63.50   $63.50  
  Purchase #2 $234.30   12.475%   $263.5289   $263.53   $263.55   $263.50  
  Purchase #3 $104.95   7.624%   $112.9514   $112.95   $112.95   $113.00  
  Purchase #4 $18.68   10.772%   $20.6922   $20.69   $20.70   $20.70  
  Purchase #5 $217.97   6.196%   $231.4754   $231.48   $231.50   $231.50  
  Purchase #6 $240.27   11.500%   $267.9011   $267.90   $267.90   $267.90  
  Purchase #7 $50.28   7.691%   $54.147   $54.15   $54.15   $54.10  
  7 purchase totals = $924.83       $1,014.1924   $1,014.20   $1,014.25   $1,014.20