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 $182.65   8.265%   $197.746   $197.75   $197.75   $197.70  
  Purchase #2 $217.65   10.864%   $241.2955   $241.30   $241.30   $241.30  
  Purchase #3 $57.40   6.271%   $60.9996   $61.00   $61.00   $61.00  
  Purchase #4 $176.27   13.740%   $200.4895   $200.49   $200.50   $200.50  
  Purchase #5 $65.36   5.786%   $69.1417   $69.14   $69.15   $69.10  
  Purchase #6 $177.60   5.488%   $187.3467   $187.35   $187.35   $187.30  
  Purchase #7 $144.93   3.784%   $150.4142   $150.41   $150.40   $150.40  
  7 purchase totals = $1,021.86       $1,107.4332   $1,107.44   $1,107.45   $1,107.30