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 $116.47   7.535%   $125.246   $125.25   $125.25   $125.20  
  Purchase #2 $211.43   7.164%   $226.5768   $226.58   $226.60   $226.60  
  Purchase #3 $44.61   4.662%   $46.6897   $46.69   $46.70   $46.70  
  Purchase #4 $93.39   3.236%   $96.4121   $96.41   $96.40   $96.40  
  Purchase #5 $70.32   7.779%   $75.7902   $75.79   $75.80   $75.80  
  Purchase #6 $202.77   6.582%   $216.1163   $216.12   $216.10   $216.10  
  Purchase #7 $245.54   7.533%   $264.0365   $264.04   $264.05   $264.00  
  7 purchase totals = $984.53       $1,050.8676   $1,050.88   $1,050.90   $1,050.80