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 $208.32   7.355%   $223.6419   $223.64   $223.65   $223.60  
  Purchase #2 $104.59   7.133%   $112.0504   $112.05   $112.05   $112.10  
  Purchase #3 $111.59   6.849%   $119.2328   $119.23   $119.25   $119.20  
  Purchase #4 $37.67   5.779%   $39.8469   $39.85   $39.85   $39.80  
  Purchase #5 $192.32   6.712%   $205.2285   $205.23   $205.25   $205.20  
  Purchase #6 $195.39   3.219%   $201.6796   $201.68   $201.70   $201.70  
  Purchase #7 $187.90   3.274%   $194.0518   $194.05   $194.05   $194.10  
  7 purchase totals = $1,037.78       $1,095.7319   $1,095.73   $1,095.80   $1,095.70