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 $88.66   7.190%   $95.0347   $95.03   $95.05   $95.00  
  Purchase #2 $201.68   12.619%   $227.13   $227.13   $227.15   $227.10  
  Purchase #3 $21.82   3.604%   $22.6064   $22.61   $22.60   $22.60  
  Purchase #4 $175.49   9.237%   $191.7   $191.70   $191.70   $191.70  
  Purchase #5 $166.65   4.190%   $173.6326   $173.63   $173.65   $173.60  
  Purchase #6 $243.34   7.684%   $262.0382   $262.04   $262.05   $262.00  
  Purchase #7 $221.91   11.370%   $247.1412   $247.14   $247.15   $247.10  
  7 purchase totals = $1,119.55       $1,219.2831   $1,219.28   $1,219.35   $1,219.10