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 $214.80   5.363%   $226.3197   $226.32   $226.30   $226.30  
  Purchase #2 $153.87   5.284%   $162.0005   $162.00   $162.00   $162.00  
  Purchase #3 $167.57   12.345%   $188.2565   $188.26   $188.25   $188.30  
  Purchase #4 $186.60   4.474%   $194.9485   $194.95   $194.95   $194.90  
  Purchase #5 $59.34   9.323%   $64.8723   $64.87   $64.85   $64.90  
  Purchase #6 $67.52   13.440%   $76.5947   $76.59   $76.60   $76.60  
  Purchase #7 $170.78   6.844%   $182.4682   $182.47   $182.45   $182.50  
  7 purchase totals = $1,020.48       $1,095.4604   $1,095.46   $1,095.40   $1,095.50