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 $119.53   4.619%   $125.0511   $125.05   $125.05   $125.10  
  Purchase #2 $192.79   7.400%   $207.0565   $207.06   $207.05   $207.10  
  Purchase #3 $175.60   10.261%   $193.6183   $193.62   $193.60   $193.60  
  Purchase #4 $186.74   5.804%   $197.5784   $197.58   $197.60   $197.60  
  Purchase #5 $214.39   13.166%   $242.6166   $242.62   $242.60   $242.60  
  Purchase #6 $100.96   9.691%   $110.744   $110.74   $110.75   $110.70  
  Purchase #7 $84.52   8.124%   $91.3864   $91.39   $91.40   $91.40  
  7 purchase totals = $1,074.53       $1,168.0513   $1,168.06   $1,168.05   $1,168.10