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	$69.84	3.305%	$72.1482	$72.15	$72.15	$72.10
Purchase #2	$202.32	10.307%	$223.1731	$223.17	$223.15	$223.20
Purchase #3	$12.65	7.406%	$13.5869	$13.59	$13.60	$13.60
Purchase #4	$197.45	13.521%	$224.1472	$224.15	$224.15	$224.10
Purchase #5	$126.39	4.190%	$131.6857	$131.69	$131.70	$131.70
Purchase #6	$131.61	12.265%	$147.752	$147.75	$147.75	$147.80
Purchase #7	$211.31	4.458%	$220.7302	$220.73	$220.75	$220.70
7 purchase totals =	$951.57		$1,033.2233	$1,033.23	$1,033.25	$1,033.20