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	$52.71	3.238%	$54.4167	$54.42	$54.40	$54.40
Purchase #2	$90.86	4.526%	$94.9723	$94.97	$94.95	$95.00
Purchase #3	$95.86	4.816%	$100.4766	$100.48	$100.50	$100.50
Purchase #4	$177.91	7.532%	$191.3102	$191.31	$191.30	$191.30
Purchase #5	$9.61	5.496%	$10.1382	$10.14	$10.15	$10.10
Purchase #6	$45.49	13.805%	$51.7699	$51.77	$51.75	$51.80
Purchase #7	$185.52	4.432%	$193.7422	$193.74	$193.75	$193.70
7 purchase totals =	$657.96		$696.8261	$696.83	$696.80	$696.80