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 $216.68   9.527%   $237.3231   $237.32   $237.30   $237.30  
  Purchase #2 $151.70   8.567%   $164.6961   $164.70   $164.70   $164.70  
  Purchase #3 $96.38   8.116%   $104.2022   $104.20   $104.20   $104.20  
  Purchase #4 $174.27   8.638%   $189.3234   $189.32   $189.30   $189.30  
  Purchase #5 $181.90   9.821%   $199.7644   $199.76   $199.75   $199.80  
  Purchase #6 $187.30   8.130%   $202.5275   $202.53   $202.55   $202.50  
  Purchase #7 $13.38   5.243%   $14.0815   $14.08   $14.10   $14.10  
  7 purchase totals = $1,021.61       $1,111.9182   $1,111.91   $1,111.90   $1,111.90