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 $108.76   4.851%   $114.0359   $114.04   $114.05   $114.00  
  Purchase #2 $178.49   8.766%   $194.1364   $194.14   $194.15   $194.10  
  Purchase #3 $167.96   7.762%   $180.9971   $181.00   $181.00   $181.00  
  Purchase #4 $27.41   11.604%   $30.5907   $30.59   $30.60   $30.60  
  Purchase #5 $67.68   13.241%   $76.6415   $76.64   $76.65   $76.60  
  Purchase #6 $193.45   6.465%   $205.9565   $205.96   $205.95   $206.00  
  Purchase #7 $223.36   8.656%   $242.694   $242.69   $242.70   $242.70  
  7 purchase totals = $967.11       $1,045.0521   $1,045.06   $1,045.10   $1,045.00