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	$239.81	10.748%	$265.5848	$265.58	$265.60	$265.60
Purchase #2	$100.62	3.608%	$104.2504	$104.25	$104.25	$104.30
Purchase #3	$218.25	11.865%	$244.1454	$244.15	$244.15	$244.10
Purchase #4	$84.75	6.842%	$90.5486	$90.55	$90.55	$90.50
Purchase #5	$13.42	4.365%	$14.0058	$14.01	$14.00	$14.00
Purchase #6	$191.73	4.572%	$200.4959	$200.50	$200.50	$200.50
Purchase #7	$212.61	7.500%	$228.5558	$228.56	$228.55	$228.60
7 purchase totals =	$1,061.19		$1,147.5867	$1,147.60	$1,147.60	$1,147.60