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 $181.26   7.597%   $195.0303   $195.03   $195.05   $195.00  
  Purchase #2 $204.46   3.513%   $211.6427   $211.64   $211.65   $211.60  
  Purchase #3 $42.26   8.606%   $45.8969   $45.90   $45.90   $45.90  
  Purchase #4 $186.73   8.270%   $202.1726   $202.17   $202.15   $202.20  
  Purchase #5 $106.77   5.442%   $112.5804   $112.58   $112.60   $112.60  
  Purchase #6 $200.58   12.435%   $225.5221   $225.52   $225.50   $225.50  
  Purchase #7 $171.45   12.320%   $192.5726   $192.57   $192.55   $192.60  
  7 purchase totals = $1,093.51       $1,185.4176   $1,185.41   $1,185.40   $1,185.40