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	$111.39	3.194%	$114.9478	$114.95	$114.95	$114.90
Purchase #2	$210.92	5.603%	$222.7378	$222.74	$222.75	$222.70
Purchase #3	$174.98	13.442%	$198.5008	$198.50	$198.50	$198.50
Purchase #4	$52.31	5.444%	$55.1578	$55.16	$55.15	$55.20
Purchase #5	$192.88	10.358%	$212.8585	$212.86	$212.85	$212.90
Purchase #6	$157.70	6.145%	$167.3907	$167.39	$167.40	$167.40
Purchase #7	$215.83	5.337%	$227.3488	$227.35	$227.35	$227.30
7 purchase totals =	$1,116.01		$1,198.9422	$1,198.95	$1,198.95	$1,198.90