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 $216.64   5.725%   $229.0426   $229.04   $229.05   $229.00  
  Purchase #2 $113.62   5.394%   $119.7487   $119.75   $119.75   $119.70  
  Purchase #3 $231.59   4.342%   $241.6456   $241.65   $241.65   $241.60  
  Purchase #4 $10.61   3.712%   $11.0038   $11.00   $11.00   $11.00  
  Purchase #5 $202.61   6.211%   $215.1941   $215.19   $215.20   $215.20  
  Purchase #6 $170.64   6.541%   $181.8016   $181.80   $181.80   $181.80  
  Purchase #7 $122.55   4.485%   $128.0464   $128.05   $128.05   $128.00  
  7 purchase totals = $1,068.26       $1,126.4828   $1,126.48   $1,126.50   $1,126.30