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	$158.45	5.707%	$167.4927	$167.49	$167.50	$167.50
Purchase #2	$26.52	8.665%	$28.818	$28.82	$28.80	$28.80
Purchase #3	$92.93	3.379%	$96.0701	$96.07	$96.05	$96.10
Purchase #4	$250.78	7.434%	$269.423	$269.42	$269.40	$269.40
Purchase #5	$214.26	5.122%	$225.2344	$225.23	$225.25	$225.20
Purchase #6	$25.42	13.738%	$28.9122	$28.91	$28.90	$28.90
Purchase #7	$202.27	11.646%	$225.8264	$225.83	$225.85	$225.80
7 purchase totals =	$970.63		$1,041.7768	$1,041.77	$1,041.75	$1,041.70