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	$152.61	3.205%	$157.5012	$157.50	$157.50	$157.50
Purchase #2	$73.77	6.608%	$78.6447	$78.64	$78.65	$78.60
Purchase #3	$247.33	12.729%	$278.8126	$278.81	$278.80	$278.80
Purchase #4	$147.49	10.871%	$163.5236	$163.52	$163.50	$163.50
Purchase #5	$159.75	4.402%	$166.7822	$166.78	$166.80	$166.80
Purchase #6	$127.68	4.109%	$132.9264	$132.93	$132.95	$132.90
Purchase #7	$165.57	5.338%	$174.4081	$174.41	$174.40	$174.40
7 purchase totals =	$1,074.20		$1,152.5988	$1,152.59	$1,152.60	$1,152.50