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 $87.78   8.223%   $94.9981   $95.00   $95.00   $95.00  
  Purchase #2 $183.98   9.442%   $201.3514   $201.35   $201.35   $201.40  
  Purchase #3 $112.99   7.810%   $121.8145   $121.81   $121.80   $121.80  
  Purchase #4 $223.41   8.703%   $242.8534   $242.85   $242.85   $242.90  
  Purchase #5 $120.64   9.339%   $131.9066   $131.91   $131.90   $131.90  
  Purchase #6 $244.38   10.384%   $269.7564   $269.76   $269.75   $269.80  
  Purchase #7 $117.87   13.493%   $133.7742   $133.77   $133.75   $133.80  
  7 purchase totals = $1,091.05       $1,196.4546   $1,196.45   $1,196.40   $1,196.60