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 $211.57   7.270%   $226.9511   $226.95   $226.95   $227.00  
  Purchase #2 $94.90   11.327%   $105.6493   $105.65   $105.65   $105.60  
  Purchase #3 $116.42   4.507%   $121.667   $121.67   $121.65   $121.70  
  Purchase #4 $153.42   9.178%   $167.5009   $167.50   $167.50   $167.50  
  Purchase #5 $39.80   3.262%   $41.0983   $41.10   $41.10   $41.10  
  Purchase #6 $245.64   4.153%   $255.8414   $255.84   $255.85   $255.80  
  Purchase #7 $167.79   5.257%   $176.6107   $176.61   $176.60   $176.60  
  7 purchase totals = $1,029.54       $1,095.3187   $1,095.32   $1,095.30   $1,095.30