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 $89.26   7.803%   $96.225   $96.23   $96.25   $96.20  
  Purchase #2 $151.98   7.367%   $163.1764   $163.18   $163.20   $163.20  
  Purchase #3 $39.88   11.865%   $44.6118   $44.61   $44.60   $44.60  
  Purchase #4 $176.82   5.201%   $186.0164   $186.02   $186.00   $186.00  
  Purchase #5 $181.44   12.661%   $204.4121   $204.41   $204.40   $204.40  
  Purchase #6 $65.98   3.526%   $68.3065   $68.31   $68.30   $68.30  
  Purchase #7 $22.63   8.365%   $24.523   $24.52   $24.50   $24.50  
  7 purchase totals = $727.99       $787.2712   $787.28   $787.25   $787.20