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 $85.89   10.559%   $94.9591   $94.96   $94.95   $95.00  
  Purchase #2 $17.92   10.517%   $19.8046   $19.80   $19.80   $19.80  
  Purchase #3 $65.47   12.601%   $73.7199   $73.72   $73.70   $73.70  
  Purchase #4 $240.82   13.174%   $272.5456   $272.55   $272.55   $272.50  
  Purchase #5 $141.43   11.204%   $157.2758   $157.28   $157.30   $157.30  
  Purchase #6 $49.61   6.141%   $52.6566   $52.66   $52.65   $52.70  
  Purchase #7 $195.60   10.255%   $215.6588   $215.66   $215.65   $215.70  
  7 purchase totals = $796.74       $886.6204   $886.63   $886.60   $886.70