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 $84.42   12.581%   $95.0409   $95.04   $95.05   $95.00  
  Purchase #2 $58.46   7.324%   $62.7416   $62.74   $62.75   $62.70  
  Purchase #3 $152.35   6.163%   $161.7393   $161.74   $161.75   $161.70  
  Purchase #4 $177.81   10.336%   $196.1884   $196.19   $196.20   $196.20  
  Purchase #5 $48.59   8.564%   $52.7512   $52.75   $52.75   $52.80  
  Purchase #6 $236.31   12.137%   $264.9909   $264.99   $265.00   $265.00  
  Purchase #7 $184.49   11.184%   $205.1234   $205.12   $205.10   $205.10  
  7 purchase totals = $942.43       $1,038.5757   $1,038.57   $1,038.60   $1,038.50