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 $69.72   5.582%   $73.6118   $73.61   $73.60   $73.60  
  Purchase #2 $192.81   12.232%   $216.3945   $216.39   $216.40   $216.40  
  Purchase #3 $113.26   10.721%   $125.4026   $125.40   $125.40   $125.40  
  Purchase #4 $217.94   11.204%   $242.358   $242.36   $242.35   $242.40  
  Purchase #5 $85.97   9.643%   $94.2601   $94.26   $94.25   $94.30  
  Purchase #6 $139.51   5.844%   $147.663   $147.66   $147.65   $147.70  
  Purchase #7 $194.33   4.239%   $202.5676   $202.57   $202.55   $202.60  
  7 purchase totals = $1,013.54       $1,102.2576   $1,102.25   $1,102.20   $1,102.40