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 $87.64   9.142%   $95.652   $95.65   $95.65   $95.70  
  Purchase #2 $243.81   4.525%   $254.8424   $254.84   $254.85   $254.80  
  Purchase #3 $51.84   10.237%   $57.1469   $57.15   $57.15   $57.10  
  Purchase #4 $140.99   8.302%   $152.695   $152.70   $152.70   $152.70  
  Purchase #5 $195.90   5.250%   $206.1848   $206.18   $206.20   $206.20  
  Purchase #6 $224.76   13.379%   $254.8306   $254.83   $254.85   $254.80  
  Purchase #7 $215.37   3.697%   $223.3322   $223.33   $223.35   $223.30  
  7 purchase totals = $1,160.31       $1,244.6839   $1,244.68   $1,244.75   $1,244.60