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 $208.48   3.137%   $215.02   $215.02   $215.00   $215.00  
  Purchase #2 $198.38   11.852%   $221.892   $221.89   $221.90   $221.90  
  Purchase #3 $85.89   11.127%   $95.447   $95.45   $95.45   $95.40  
  Purchase #4 $83.38   9.718%   $91.4829   $91.48   $91.50   $91.50  
  Purchase #5 $170.29   10.249%   $187.743   $187.74   $187.75   $187.70  
  Purchase #6 $56.95   8.864%   $61.998   $62.00   $62.00   $62.00  
  Purchase #7 $230.31   6.573%   $245.4483   $245.45   $245.45   $245.40  
  7 purchase totals = $1,033.68       $1,119.0312   $1,119.03   $1,119.05   $1,118.90