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 $214.99   5.717%   $227.281   $227.28   $227.30   $227.30  
  Purchase #2 $71.81   3.792%   $74.533   $74.53   $74.55   $74.50  
  Purchase #3 $84.94   3.420%   $87.8449   $87.84   $87.85   $87.80  
  Purchase #4 $90.74   4.665%   $94.973   $94.97   $94.95   $95.00  
  Purchase #5 $103.86   12.499%   $116.8415   $116.84   $116.85   $116.80  
  Purchase #6 $47.94   13.813%   $54.562   $54.56   $54.55   $54.60  
  Purchase #7 $90.60   6.501%   $96.4899   $96.49   $96.50   $96.50  
  7 purchase totals = $704.88       $752.5253   $752.51   $752.55   $752.50