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 $172.26   13.110%   $194.8433   $194.84   $194.85   $194.80  
  Purchase #2 $118.87   4.416%   $124.1193   $124.12   $124.10   $124.10  
  Purchase #3 $73.55   10.425%   $81.2176   $81.22   $81.20   $81.20  
  Purchase #4 $211.93   9.789%   $232.6758   $232.68   $232.70   $232.70  
  Purchase #5 $88.89   13.430%   $100.8279   $100.83   $100.85   $100.80  
  Purchase #6 $126.40   13.745%   $143.7737   $143.77   $143.75   $143.80  
  Purchase #7 $176.52   3.124%   $182.0345   $182.03   $182.05   $182.00  
  7 purchase totals = $968.42       $1,059.4921   $1,059.49   $1,059.50   $1,059.40