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 $216.68   11.511%   $241.622   $241.62   $241.60   $241.60  
  Purchase #2 $70.77   3.519%   $73.2604   $73.26   $73.25   $73.30  
  Purchase #3 $63.93   6.345%   $67.9864   $67.99   $68.00   $68.00  
  Purchase #4 $198.59   4.632%   $207.7887   $207.79   $207.80   $207.80  
  Purchase #5 $243.73   7.441%   $261.8659   $261.87   $261.85   $261.90  
  Purchase #6 $119.59   8.794%   $130.1067   $130.11   $130.10   $130.10  
  Purchase #7 $105.28   6.721%   $112.3559   $112.36   $112.35   $112.40  
  7 purchase totals = $1,018.57       $1,094.9860   $1,095.00   $1,094.95   $1,095.10