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 $52.69   5.226%   $55.4436   $55.44   $55.45   $55.40  
  Purchase #2 $225.39   5.810%   $238.4852   $238.49   $238.50   $238.50  
  Purchase #3 $55.45   3.771%   $57.541   $57.54   $57.55   $57.50  
  Purchase #4 $206.29   10.301%   $227.5399   $227.54   $227.55   $227.50  
  Purchase #5 $41.37   6.338%   $43.992   $43.99   $44.00   $44.00  
  Purchase #6 $239.28   4.306%   $249.5834   $249.58   $249.60   $249.60  
  Purchase #7 $211.50   5.516%   $223.1663   $223.17   $223.15   $223.20  
  7 purchase totals = $1,031.97       $1,095.7514   $1,095.75   $1,095.80   $1,095.70