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 $71.34   7.861%   $76.948   $76.95   $76.95   $76.90  
  Purchase #2 $237.57   8.746%   $258.3479   $258.35   $258.35   $258.30  
  Purchase #3 $243.47   11.831%   $272.2749   $272.27   $272.25   $272.30  
  Purchase #4 $167.90   4.661%   $175.7258   $175.73   $175.75   $175.70  
  Purchase #5 $176.65   9.481%   $193.3982   $193.40   $193.40   $193.40  
  Purchase #6 $221.35   3.685%   $229.5067   $229.51   $229.50   $229.50  
  Purchase #7 $242.79   5.209%   $255.4369   $255.44   $255.45   $255.40  
  7 purchase totals = $1,361.07       $1,461.6384   $1,461.65   $1,461.65   $1,461.50