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 $86.39   10.705%   $95.638   $95.64   $95.65   $95.60  
  Purchase #2 $175.32   10.453%   $193.6462   $193.65   $193.65   $193.60  
  Purchase #3 $159.86   3.240%   $165.0395   $165.04   $165.05   $165.00  
  Purchase #4 $185.27   9.792%   $203.4116   $203.41   $203.40   $203.40  
  Purchase #5 $119.65   3.255%   $123.5446   $123.54   $123.55   $123.50  
  Purchase #6 $135.65   3.181%   $139.965   $139.97   $139.95   $140.00  
  Purchase #7 $142.32   4.834%   $149.1997   $149.20   $149.20   $149.20  
  7 purchase totals = $1,004.46       $1,070.4446   $1,070.45   $1,070.45   $1,070.30