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 $195.72   4.717%   $204.9521   $204.95   $204.95   $205.00  
  Purchase #2 $88.33   7.294%   $94.7728   $94.77   $94.75   $94.80  
  Purchase #3 $116.83   10.204%   $128.7513   $128.75   $128.75   $128.80  
  Purchase #4 $212.94   3.469%   $220.3269   $220.33   $220.35   $220.30  
  Purchase #5 $58.89   4.362%   $61.4588   $61.46   $61.45   $61.50  
  Purchase #6 $248.58   10.754%   $275.3123   $275.31   $275.30   $275.30  
  Purchase #7 $182.65   7.302%   $195.9871   $195.99   $196.00   $196.00  
  7 purchase totals = $1,103.94       $1,181.5613   $1,181.56   $1,181.55   $1,181.70