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 $88.42   7.409%   $94.971   $94.97   $94.95   $95.00  
  Purchase #2 $123.87   3.235%   $127.8772   $127.88   $127.90   $127.90  
  Purchase #3 $244.93   12.317%   $275.098   $275.10   $275.10   $275.10  
  Purchase #4 $230.59   7.807%   $248.5922   $248.59   $248.60   $248.60  
  Purchase #5 $81.27   6.683%   $86.7013   $86.70   $86.70   $86.70  
  Purchase #6 $114.87   9.271%   $125.5196   $125.52   $125.50   $125.50  
  Purchase #7 $167.45   4.573%   $175.1075   $175.11   $175.10   $175.10  
  7 purchase totals = $1,051.40       $1,133.8668   $1,133.87   $1,133.85   $1,133.90