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 $58.95   5.727%   $62.3261   $62.33   $62.35   $62.30  
  Purchase #2 $201.53   9.502%   $220.6794   $220.68   $220.70   $220.70  
  Purchase #3 $183.30   4.627%   $191.7813   $191.78   $191.80   $191.80  
  Purchase #4 $155.58   5.155%   $163.6001   $163.60   $163.60   $163.60  
  Purchase #5 $144.35   8.379%   $156.4451   $156.45   $156.45   $156.40  
  Purchase #6 $82.85   3.261%   $85.5517   $85.55   $85.55   $85.60  
  Purchase #7 $239.28   3.541%   $247.7529   $247.75   $247.75   $247.80  
  7 purchase totals = $1,065.84       $1,128.1366   $1,128.14   $1,128.20   $1,128.20