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	$149.71	8.842%	$162.9474	$162.95	$162.95	$162.90
Purchase #2	$144.64	3.360%	$149.4999	$149.50	$149.50	$149.50
Purchase #3	$141.49	8.377%	$153.3426	$153.34	$153.35	$153.30
Purchase #4	$238.93	11.674%	$266.8227	$266.82	$266.80	$266.80
Purchase #5	$106.96	3.814%	$111.0395	$111.04	$111.05	$111.00
Purchase #6	$84.47	12.139%	$94.7238	$94.72	$94.70	$94.70
Purchase #7	$56.25	10.142%	$61.9549	$61.95	$61.95	$62.00
7 purchase totals =	$922.45		$1,000.3308	$1,000.32	$1,000.30	$1,000.20