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 $65.26   5.709%   $68.9857   $68.99   $69.00   $69.00  
  Purchase #2 $195.70   11.820%   $218.8317   $218.83   $218.85   $218.80  
  Purchase #3 $159.27   13.681%   $181.0597   $181.06   $181.05   $181.10  
  Purchase #4 $95.75   5.151%   $100.6821   $100.68   $100.70   $100.70  
  Purchase #5 $225.26   3.666%   $233.518   $233.52   $233.50   $233.50  
  Purchase #6 $228.59   3.831%   $237.3473   $237.35   $237.35   $237.30  
  Purchase #7 $161.48   4.225%   $168.3025   $168.30   $168.30   $168.30  
  7 purchase totals = $1,131.31       $1,208.7270   $1,208.73   $1,208.75   $1,208.70