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 $146.74   3.558%   $151.961   $151.96   $151.95   $152.00  
  Purchase #2 $191.91   3.445%   $198.5213   $198.52   $198.50   $198.50  
  Purchase #3 $191.58   13.569%   $217.5755   $217.58   $217.60   $217.60  
  Purchase #4 $43.99   6.723%   $46.9474   $46.95   $46.95   $46.90  
  Purchase #5 $104.77   7.147%   $112.2579   $112.26   $112.25   $112.30  
  Purchase #6 $168.79   8.482%   $183.1068   $183.11   $183.10   $183.10  
  Purchase #7 $236.27   6.650%   $251.982   $251.98   $252.00   $252.00  
  7 purchase totals = $1,084.05       $1,162.3519   $1,162.36   $1,162.35   $1,162.40