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 $71.95   5.587%   $75.9698   $75.97   $75.95   $76.00  
  Purchase #2 $118.30   5.536%   $124.8491   $124.85   $124.85   $124.80  
  Purchase #3 $10.93   11.341%   $12.1696   $12.17   $12.15   $12.20  
  Purchase #4 $216.99   5.482%   $228.8854   $228.89   $228.90   $228.90  
  Purchase #5 $239.67   4.678%   $250.8818   $250.88   $250.90   $250.90  
  Purchase #6 $32.30   6.833%   $34.5071   $34.51   $34.50   $34.50  
  Purchase #7 $162.62   3.177%   $167.7864   $167.79   $167.80   $167.80  
  7 purchase totals = $852.76       $895.0492   $895.06   $895.05   $895.10