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 $84.89   12.144%   $95.199   $95.20   $95.20   $95.20  
  Purchase #2 $95.57   11.102%   $106.1802   $106.18   $106.20   $106.20  
  Purchase #3 $39.94   4.230%   $41.6295   $41.63   $41.65   $41.60  
  Purchase #4 $32.83   7.734%   $35.3691   $35.37   $35.35   $35.40  
  Purchase #5 $158.96   10.192%   $175.1612   $175.16   $175.15   $175.20  
  Purchase #6 $85.68   3.210%   $88.4303   $88.43   $88.45   $88.40  
  Purchase #7 $215.45   7.739%   $232.1237   $232.12   $232.10   $232.10  
  7 purchase totals = $713.32       $774.0930   $774.09   $774.10   $774.10