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	$202.27	3.110%	$208.5606	$208.56	$208.55	$208.60
Purchase #2	$150.89	10.746%	$167.1046	$167.10	$167.10	$167.10
Purchase #3	$28.41	10.839%	$31.4894	$31.49	$31.50	$31.50
Purchase #4	$210.87	5.535%	$222.5417	$222.54	$222.55	$222.50
Purchase #5	$173.87	9.746%	$190.8154	$190.82	$190.80	$190.80
Purchase #6	$250.95	13.597%	$285.0717	$285.07	$285.05	$285.10
Purchase #7	$110.41	10.104%	$121.5658	$121.57	$121.55	$121.60
7 purchase totals =	$1,127.67		$1,227.1492	$1,227.15	$1,227.10	$1,227.20