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 $213.77   10.201%   $235.5767   $235.58   $235.60   $235.60  
  Purchase #2 $189.39   11.741%   $211.6263   $211.63   $211.65   $211.60  
  Purchase #3 $153.51   10.358%   $169.4106   $169.41   $169.40   $169.40  
  Purchase #4 $162.25   8.696%   $176.3593   $176.36   $176.35   $176.40  
  Purchase #5 $151.68   10.817%   $168.0872   $168.09   $168.10   $168.10  
  Purchase #6 $214.33   7.283%   $229.9397   $229.94   $229.95   $229.90  
  Purchase #7 $247.90   11.222%   $275.7193   $275.72   $275.70   $275.70  
  7 purchase totals = $1,332.83       $1,466.7191   $1,466.73   $1,466.75   $1,466.70