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 $86.59   9.695%   $94.9849   $94.98   $95.00   $95.00  
  Purchase #2 $13.59   8.651%   $14.7657   $14.77   $14.75   $14.80  
  Purchase #3 $94.59   8.562%   $102.6888   $102.69   $102.70   $102.70  
  Purchase #4 $183.70   8.186%   $198.7377   $198.74   $198.75   $198.70  
  Purchase #5 $142.65   11.850%   $159.554   $159.55   $159.55   $159.60  
  Purchase #6 $119.46   7.585%   $128.521   $128.52   $128.50   $128.50  
  Purchase #7 $216.88   10.520%   $239.6958   $239.70   $239.70   $239.70  
  7 purchase totals = $857.46       $938.9479   $938.95   $938.95   $939.00