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 $86.87   9.482%   $95.107   $95.11   $95.10   $95.10  
  Purchase #2 $89.59   7.583%   $96.3836   $96.38   $96.40   $96.40  
  Purchase #3 $69.82   5.207%   $73.4555   $73.46   $73.45   $73.50  
  Purchase #4 $50.75   5.290%   $53.4347   $53.43   $53.45   $53.40  
  Purchase #5 $190.30   10.564%   $210.4033   $210.40   $210.40   $210.40  
  Purchase #6 $176.30   11.773%   $197.0558   $197.06   $197.05   $197.10  
  Purchase #7 $185.30   8.144%   $200.3908   $200.39   $200.40   $200.40  
  7 purchase totals = $848.93       $926.2307   $926.23   $926.25   $926.30