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 $67.95   9.426%   $74.355   $74.36   $74.35   $74.40  
  Purchase #2 $169.27   7.742%   $182.3749   $182.37   $182.35   $182.40  
  Purchase #3 $101.27   8.810%   $110.1919   $110.19   $110.20   $110.20  
  Purchase #4 $103.96   8.635%   $112.9369   $112.94   $112.95   $112.90  
  Purchase #5 $249.25   12.185%   $279.6211   $279.62   $279.60   $279.60  
  Purchase #6 $168.94   4.694%   $176.87   $176.87   $176.85   $176.90  
  Purchase #7 $154.57   3.375%   $159.7867   $159.79   $159.80   $159.80  
  7 purchase totals = $1,015.21       $1,096.1365   $1,096.14   $1,096.10   $1,096.20