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	$154.71	11.563%	$172.5991	$172.60	$172.60	$172.60
Purchase #2	$120.56	11.539%	$134.4714	$134.47	$134.45	$134.50
Purchase #3	$127.50	13.518%	$144.7355	$144.74	$144.75	$144.70
Purchase #4	$157.26	9.834%	$172.7249	$172.72	$172.70	$172.70
Purchase #5	$19.93	8.519%	$21.6278	$21.63	$21.65	$21.60
Purchase #6	$218.98	11.653%	$244.4977	$244.50	$244.50	$244.50
Purchase #7	$121.65	8.440%	$131.9173	$131.92	$131.90	$131.90
7 purchase totals =	$920.59		$1,022.5737	$1,022.58	$1,022.55	$1,022.50