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 $192.95   6.510%   $205.511   $205.51   $205.50   $205.50  
  Purchase #2 $69.58   13.667%   $79.0895   $79.09   $79.10   $79.10  
  Purchase #3 $110.71   6.688%   $118.1143   $118.11   $118.10   $118.10  
  Purchase #4 $244.55   5.776%   $258.6752   $258.68   $258.70   $258.70  
  Purchase #5 $43.61   13.482%   $49.4895   $49.49   $49.50   $49.50  
  Purchase #6 $164.79   4.726%   $172.578   $172.58   $172.60   $172.60  
  Purchase #7 $197.98   6.834%   $211.51   $211.51   $211.50   $211.50  
  7 purchase totals = $1,024.17       $1,094.9675   $1,094.97   $1,095.00   $1,095.00