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 $88.61   8.296%   $95.9611   $95.96   $95.95   $96.00  
  Purchase #2 $174.33   12.592%   $196.2816   $196.28   $196.30   $196.30  
  Purchase #3 $16.32   9.431%   $17.8591   $17.86   $17.85   $17.90  
  Purchase #4 $215.47   9.143%   $235.1704   $235.17   $235.15   $235.20  
  Purchase #5 $189.88   4.276%   $197.9993   $198.00   $198.00   $198.00  
  Purchase #6 $135.46   3.211%   $139.8096   $139.81   $139.80   $139.80  
  Purchase #7 $216.32   3.668%   $224.2546   $224.25   $224.25   $224.30  
  7 purchase totals = $1,036.39       $1,107.3357   $1,107.33   $1,107.30   $1,107.50