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 $58.53   7.546%   $62.9467   $62.95   $62.95   $62.90  
  Purchase #2 $217.80   8.163%   $235.579   $235.58   $235.60   $235.60  
  Purchase #3 $147.31   11.662%   $164.4893   $164.49   $164.50   $164.50  
  Purchase #4 $27.77   8.356%   $30.0905   $30.09   $30.10   $30.10  
  Purchase #5 $210.77   11.157%   $234.2856   $234.29   $234.30   $234.30  
  Purchase #6 $240.72   6.153%   $255.5315   $255.53   $255.55   $255.50  
  Purchase #7 $153.88   10.272%   $169.6866   $169.69   $169.70   $169.70  
  7 purchase totals = $1,056.78       $1,152.6092   $1,152.62   $1,152.70   $1,152.60