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 $56.56   7.668%   $60.897   $60.90   $60.90   $60.90  
  Purchase #2 $203.94   6.576%   $217.3511   $217.35   $217.35   $217.40  
  Purchase #3 $111.95   10.273%   $123.4506   $123.45   $123.45   $123.50  
  Purchase #4 $220.99   9.664%   $242.3465   $242.35   $242.35   $242.30  
  Purchase #5 $23.52   12.609%   $26.4856   $26.49   $26.50   $26.50  
  Purchase #6 $200.78   4.323%   $209.4597   $209.46   $209.45   $209.50  
  Purchase #7 $194.78   10.679%   $215.5806   $215.58   $215.60   $215.60  
  7 purchase totals = $1,012.52       $1,095.5711   $1,095.58   $1,095.60   $1,095.70