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 $193.50   7.330%   $207.6836   $207.68   $207.70   $207.70  
  Purchase #2 $176.46   3.329%   $182.3344   $182.33   $182.35   $182.30  
  Purchase #3 $106.36   10.513%   $117.5416   $117.54   $117.55   $117.50  
  Purchase #4 $27.37   8.327%   $29.6491   $29.65   $29.65   $29.60  
  Purchase #5 $188.72   6.658%   $201.285   $201.29   $201.30   $201.30  
  Purchase #6 $241.89   5.737%   $255.7672   $255.77   $255.75   $255.80  
  Purchase #7 $90.27   12.523%   $101.5745   $101.57   $101.55   $101.60  
  7 purchase totals = $1,024.57       $1,095.8354   $1,095.83   $1,095.85   $1,095.80