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 $92.56   4.795%   $96.9983   $97.00   $97.00   $97.00  
  Purchase #2 $211.28   7.109%   $226.2999   $226.30   $226.30   $226.30  
  Purchase #3 $52.30   3.276%   $54.0133   $54.01   $54.00   $54.00  
  Purchase #4 $242.48   6.759%   $258.8692   $258.87   $258.85   $258.90  
  Purchase #5 $224.45   13.218%   $254.1178   $254.12   $254.10   $254.10  
  Purchase #6 $205.32   7.835%   $221.4068   $221.41   $221.40   $221.40  
  Purchase #7 $234.76   9.156%   $256.2546   $256.25   $256.25   $256.30  
  7 purchase totals = $1,263.15       $1,367.9599   $1,367.96   $1,367.90   $1,368.00