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 $215.90   9.169%   $235.6959   $235.70   $235.70   $235.70  
  Purchase #2 $81.93   13.453%   $92.952   $92.95   $92.95   $93.00  
  Purchase #3 $51.98   5.832%   $55.0115   $55.01   $55.00   $55.00  
  Purchase #4 $213.62   5.813%   $226.0377   $226.04   $226.05   $226.00  
  Purchase #5 $213.84   10.168%   $235.5833   $235.58   $235.60   $235.60  
  Purchase #6 $232.78   8.383%   $252.2939   $252.29   $252.30   $252.30  
  Purchase #7 $57.61   11.760%   $64.3849   $64.38   $64.40   $64.40  
  7 purchase totals = $1,067.66       $1,161.9592   $1,161.95   $1,162.00   $1,162.00