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 $91.79   3.454%   $94.9604   $94.96   $94.95   $95.00  
  Purchase #2 $225.93   7.862%   $243.6926   $243.69   $243.70   $243.70  
  Purchase #3 $174.71   3.678%   $181.1358   $181.14   $181.15   $181.10  
  Purchase #4 $149.92   6.219%   $159.2435   $159.24   $159.25   $159.20  
  Purchase #5 $100.86   9.521%   $110.4629   $110.46   $110.45   $110.50  
  Purchase #6 $195.48   10.417%   $215.8432   $215.84   $215.85   $215.80  
  Purchase #7 $180.91   11.861%   $202.3677   $202.37   $202.35   $202.40  
  7 purchase totals = $1,119.60       $1,207.7061   $1,207.70   $1,207.70   $1,207.70