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 $69.95   8.615%   $75.9762   $75.98   $76.00   $76.00  
  Purchase #2 $205.98   8.226%   $222.9239   $222.92   $222.90   $222.90  
  Purchase #3 $168.31   5.229%   $177.1109   $177.11   $177.10   $177.10  
  Purchase #4 $42.62   10.756%   $47.2042   $47.20   $47.20   $47.20  
  Purchase #5 $145.58   6.678%   $155.3018   $155.30   $155.30   $155.30  
  Purchase #6 $201.71   11.198%   $224.2975   $224.30   $224.30   $224.30  
  Purchase #7 $188.82   10.743%   $209.1049   $209.10   $209.10   $209.10  
  7 purchase totals = $1,022.97       $1,111.9194   $1,111.91   $1,111.90   $1,111.90