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 $118.48   5.527%   $125.0284   $125.03   $125.05   $125.00  
  Purchase #2 $184.51   13.586%   $209.5775   $209.58   $209.60   $209.60  
  Purchase #3 $225.51   8.658%   $245.0347   $245.03   $245.05   $245.00  
  Purchase #4 $197.88   3.282%   $204.3744   $204.37   $204.35   $204.40  
  Purchase #5 $33.55   3.137%   $34.6025   $34.60   $34.60   $34.60  
  Purchase #6 $227.68   5.382%   $239.9337   $239.93   $239.95   $239.90  
  Purchase #7 $49.72   6.137%   $52.7713   $52.77   $52.75   $52.80  
  7 purchase totals = $1,037.33       $1,111.3225   $1,111.31   $1,111.35   $1,111.30