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	$134.94	12.736%	$152.126	$152.13	$152.15	$152.10
Purchase #2	$172.42	5.184%	$181.3583	$181.36	$181.35	$181.40
Purchase #3	$193.46	3.730%	$200.6761	$200.68	$200.70	$200.70
Purchase #4	$200.83	10.746%	$222.4112	$222.41	$222.40	$222.40
Purchase #5	$66.55	6.613%	$70.951	$70.95	$70.95	$71.00
Purchase #6	$152.59	3.159%	$157.4103	$157.41	$157.40	$157.40
Purchase #7	$229.75	5.532%	$242.4598	$242.46	$242.45	$242.50
7 purchase totals =	$1,150.54		$1,227.3927	$1,227.40	$1,227.40	$1,227.50