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 $180.66   8.324%   $195.6981   $195.70   $195.70   $195.70  
  Purchase #2 $109.44   6.194%   $116.2187   $116.22   $116.20   $116.20  
  Purchase #3 $65.85   6.826%   $70.3449   $70.34   $70.35   $70.30  
  Purchase #4 $243.41   7.712%   $262.1818   $262.18   $262.20   $262.20  
  Purchase #5 $101.51   3.578%   $105.142   $105.14   $105.15   $105.10  
  Purchase #6 $223.68   10.377%   $246.8913   $246.89   $246.90   $246.90  
  Purchase #7 $51.69   9.623%   $56.6641   $56.66   $56.65   $56.70  
  7 purchase totals = $976.24       $1,053.1409   $1,053.13   $1,053.15   $1,053.10