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 $93.26   3.205%   $96.249   $96.25   $96.25   $96.20  
  Purchase #2 $97.77   3.479%   $101.1714   $101.17   $101.15   $101.20  
  Purchase #3 $82.51   13.771%   $93.8725   $93.87   $93.85   $93.90  
  Purchase #4 $224.27   9.307%   $245.1428   $245.14   $245.15   $245.10  
  Purchase #5 $183.81   11.321%   $204.6191   $204.62   $204.60   $204.60  
  Purchase #6 $228.87   6.490%   $243.7237   $243.72   $243.70   $243.70  
  Purchase #7 $118.47   4.515%   $123.8189   $123.82   $123.80   $123.80  
  7 purchase totals = $1,028.96       $1,108.5974   $1,108.59   $1,108.50   $1,108.50