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	$118.71	10.397%	$131.0523	$131.05	$131.05	$131.10
Purchase #2	$98.88	6.460%	$105.2676	$105.27	$105.25	$105.30
Purchase #3	$23.89	5.557%	$25.2176	$25.22	$25.20	$25.20
Purchase #4	$142.72	11.222%	$158.736	$158.74	$158.75	$158.70
Purchase #5	$22.70	11.249%	$25.2535	$25.25	$25.25	$25.30
Purchase #6	$22.52	13.225%	$25.4983	$25.50	$25.50	$25.50
Purchase #7	$223.37	13.689%	$253.9471	$253.95	$253.95	$253.90
7 purchase totals =	$652.79		$724.9724	$724.98	$724.95	$725.00