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 $59.33   7.396%   $63.718   $63.72   $63.70   $63.70  
  Purchase #2 $193.90   6.874%   $207.2287   $207.23   $207.25   $207.20  
  Purchase #3 $242.65   13.592%   $275.631   $275.63   $275.65   $275.60  
  Purchase #4 $127.52   8.799%   $138.7405   $138.74   $138.75   $138.70  
  Purchase #5 $44.82   5.816%   $47.4267   $47.43   $47.45   $47.40  
  Purchase #6 $226.89   6.515%   $241.6719   $241.67   $241.65   $241.70  
  Purchase #7 $37.58   5.675%   $39.7127   $39.71   $39.70   $39.70  
  7 purchase totals = $932.69       $1,014.1295   $1,014.13   $1,014.15   $1,014.00