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 $119.61   4.694%   $125.2245   $125.22   $125.20   $125.20  
  Purchase #2 $239.54   13.712%   $272.3857   $272.39   $272.40   $272.40  
  Purchase #3 $219.58   3.558%   $227.3927   $227.39   $227.40   $227.40  
  Purchase #4 $46.29   9.214%   $50.5552   $50.56   $50.55   $50.60  
  Purchase #5 $195.70   3.807%   $203.1503   $203.15   $203.15   $203.20  
  Purchase #6 $55.60   3.477%   $57.5332   $57.53   $57.55   $57.50  
  Purchase #7 $157.43   13.184%   $178.1856   $178.19   $178.20   $178.20  
  7 purchase totals = $1,033.75       $1,114.4272   $1,114.43   $1,114.45   $1,114.50