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 $208.26   11.204%   $231.5935   $231.59   $231.60   $231.60  
  Purchase #2 $200.86   4.154%   $209.2037   $209.20   $209.20   $209.20  
  Purchase #3 $206.82   12.562%   $232.8007   $232.80   $232.80   $232.80  
  Purchase #4 $248.93   9.748%   $273.1957   $273.20   $273.20   $273.20  
  Purchase #5 $97.90   10.322%   $108.0052   $108.01   $108.00   $108.00  
  Purchase #6 $214.99   5.697%   $227.238   $227.24   $227.25   $227.20  
  Purchase #7 $185.62   3.490%   $192.0981   $192.10   $192.10   $192.10  
  7 purchase totals = $1,363.38       $1,474.1349   $1,474.14   $1,474.15   $1,474.10