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 $176.76   10.184%   $194.7612   $194.76   $194.75   $194.80  
  Purchase #2 $48.80   12.603%   $54.9503   $54.95   $54.95   $55.00  
  Purchase #3 $158.98   5.784%   $168.1754   $168.18   $168.20   $168.20  
  Purchase #4 $193.26   13.773%   $219.8777   $219.88   $219.90   $219.90  
  Purchase #5 $155.88   8.422%   $169.0082   $169.01   $169.00   $169.00  
  Purchase #6 $145.37   7.466%   $156.2233   $156.22   $156.20   $156.20  
  Purchase #7 $146.29   5.210%   $153.9117   $153.91   $153.90   $153.90  
  7 purchase totals = $1,025.34       $1,116.9078   $1,116.91   $1,116.90   $1,117.00