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 $224.61   7.430%   $241.2985   $241.30   $241.30   $241.30  
  Purchase #2 $113.94   4.670%   $119.261   $119.26   $119.25   $119.30  
  Purchase #3 $169.43   3.837%   $175.931   $175.93   $175.95   $175.90  
  Purchase #4 $69.89   4.605%   $73.1084   $73.11   $73.10   $73.10  
  Purchase #5 $176.50   10.475%   $194.9884   $194.99   $195.00   $195.00  
  Purchase #6 $45.27   5.662%   $47.8332   $47.83   $47.85   $47.80  
  Purchase #7 $194.96   3.628%   $202.0331   $202.03   $202.05   $202.00  
  7 purchase totals = $994.60       $1,054.4536   $1,054.45   $1,054.50   $1,054.40