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 $59.44   4.221%   $61.949   $61.95   $61.95   $61.90  
  Purchase #2 $157.87   12.741%   $177.9842   $177.98   $178.00   $178.00  
  Purchase #3 $29.34   7.252%   $31.4677   $31.47   $31.45   $31.50  
  Purchase #4 $178.73   8.426%   $193.7898   $193.79   $193.80   $193.80  
  Purchase #5 $157.82   6.513%   $168.0988   $168.10   $168.10   $168.10  
  Purchase #6 $249.53   9.458%   $273.1305   $273.13   $273.15   $273.10  
  Purchase #7 $215.35   11.537%   $240.1949   $240.19   $240.20   $240.20  
  7 purchase totals = $1,048.08       $1,146.6149   $1,146.61   $1,146.65   $1,146.60