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 $87.31   7.661%   $93.9988   $94.00   $94.00   $94.00  
  Purchase #2 $182.69   8.446%   $198.12   $198.12   $198.10   $198.10  
  Purchase #3 $83.64   12.681%   $94.2464   $94.25   $94.25   $94.20  
  Purchase #4 $166.92   3.369%   $172.5435   $172.54   $172.55   $172.50  
  Purchase #5 $53.86   11.509%   $60.0587   $60.06   $60.05   $60.10  
  Purchase #6 $56.59   13.203%   $64.0616   $64.06   $64.05   $64.10  
  Purchase #7 $70.27   4.189%   $73.2136   $73.21   $73.20   $73.20  
  7 purchase totals = $701.28       $756.2426   $756.24   $756.20   $756.20