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 $86.26   10.122%   $94.9912   $94.99   $95.00   $95.00  
  Purchase #2 $206.66   12.469%   $232.4284   $232.43   $232.45   $232.40  
  Purchase #3 $34.49   11.796%   $38.5584   $38.56   $38.55   $38.60  
  Purchase #4 $170.28   3.621%   $176.4458   $176.45   $176.45   $176.40  
  Purchase #5 $47.71   9.432%   $52.21   $52.21   $52.20   $52.20  
  Purchase #6 $111.57   11.814%   $124.7509   $124.75   $124.75   $124.80  
  Purchase #7 $58.25   6.342%   $61.9442   $61.94   $61.95   $61.90  
  7 purchase totals = $715.22       $781.3289   $781.33   $781.35   $781.30