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 $183.82   5.556%   $194.033   $194.03   $194.05   $194.00  
  Purchase #2 $230.95   5.862%   $244.4883   $244.49   $244.50   $244.50  
  Purchase #3 $229.32   5.855%   $242.7467   $242.75   $242.75   $242.70  
  Purchase #4 $136.76   13.439%   $155.1392   $155.14   $155.15   $155.10  
  Purchase #5 $184.29   3.668%   $191.0498   $191.05   $191.05   $191.00  
  Purchase #6 $24.42   3.555%   $25.2881   $25.29   $25.30   $25.30  
  Purchase #7 $111.88   10.176%   $123.2649   $123.26   $123.25   $123.30  
  7 purchase totals = $1,101.44       $1,176.0100   $1,176.01   $1,176.05   $1,175.90