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 $134.95   9.607%   $147.9146   $147.91   $147.90   $147.90  
  Purchase #2 $35.65   4.582%   $37.2835   $37.28   $37.30   $37.30  
  Purchase #3 $184.28   5.280%   $194.01   $194.01   $194.00   $194.00  
  Purchase #4 $94.60   13.543%   $107.4117   $107.41   $107.40   $107.40  
  Purchase #5 $152.58   7.498%   $164.0204   $164.02   $164.00   $164.00  
  Purchase #6 $191.87   6.800%   $204.9172   $204.92   $204.90   $204.90  
  Purchase #7 $244.52   6.745%   $261.0129   $261.01   $261.00   $261.00  
  7 purchase totals = $1,038.45       $1,116.5703   $1,116.56   $1,116.50   $1,116.50