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 $194.26   3.313%   $200.6958   $200.70   $200.70   $200.70  
  Purchase #2 $15.83   7.151%   $16.962   $16.96   $16.95   $17.00  
  Purchase #3 $189.32   6.679%   $201.9647   $201.96   $201.95   $202.00  
  Purchase #4 $49.76   6.745%   $53.1163   $53.12   $53.10   $53.10  
  Purchase #5 $187.42   8.585%   $203.51   $203.51   $203.50   $203.50  
  Purchase #6 $188.74   11.388%   $210.2337   $210.23   $210.25   $210.20  
  Purchase #7 $190.41   9.252%   $208.0267   $208.03   $208.05   $208.00  
  7 purchase totals = $1,015.74       $1,094.5092   $1,094.51   $1,094.50   $1,094.50