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 $92.58   3.681%   $95.9879   $95.99   $96.00   $96.00  
  Purchase #2 $34.86   4.412%   $36.398   $36.40   $36.40   $36.40  
  Purchase #3 $176.90   10.753%   $195.9221   $195.92   $195.90   $195.90  
  Purchase #4 $205.36   11.367%   $228.7033   $228.70   $228.70   $228.70  
  Purchase #5 $86.45   7.565%   $92.9899   $92.99   $93.00   $93.00  
  Purchase #6 $115.51   7.260%   $123.896   $123.90   $123.90   $123.90  
  Purchase #7 $211.38   13.864%   $240.6857   $240.69   $240.70   $240.70  
  7 purchase totals = $923.04       $1,014.5829   $1,014.59   $1,014.60   $1,014.60