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 $206.49   3.184%   $213.0646   $213.06   $213.05   $213.10  
  Purchase #2 $54.92   3.847%   $57.0328   $57.03   $57.05   $57.00  
  Purchase #3 $246.29   7.332%   $264.348   $264.35   $264.35   $264.30  
  Purchase #4 $177.28   7.621%   $190.7905   $190.79   $190.80   $190.80  
  Purchase #5 $77.95   8.609%   $84.6607   $84.66   $84.65   $84.70  
  Purchase #6 $198.65   6.242%   $211.0497   $211.05   $211.05   $211.00  
  Purchase #7 $66.94   11.346%   $74.535   $74.54   $74.55   $74.50  
  7 purchase totals = $1,028.52       $1,095.4813   $1,095.48   $1,095.50   $1,095.40