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 $194.82   3.649%   $201.929   $201.93   $201.95   $201.90  
  Purchase #2 $144.26   8.380%   $156.349   $156.35   $156.35   $156.30  
  Purchase #3 $240.99   10.227%   $265.636   $265.64   $265.65   $265.60  
  Purchase #4 $65.58   4.598%   $68.5954   $68.60   $68.60   $68.60  
  Purchase #5 $188.52   9.119%   $205.7111   $205.71   $205.70   $205.70  
  Purchase #6 $185.99   3.450%   $192.4067   $192.41   $192.40   $192.40  
  Purchase #7 $189.56   7.750%   $204.2509   $204.25   $204.25   $204.30  
  7 purchase totals = $1,209.72       $1,294.8781   $1,294.89   $1,294.90   $1,294.80