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	$245.95	9.171%	$268.5061	$268.51	$268.50	$268.50
Purchase #2	$29.31	13.566%	$33.2862	$33.29	$33.30	$33.30
Purchase #3	$212.93	13.431%	$241.5286	$241.53	$241.55	$241.50
Purchase #4	$124.65	5.539%	$131.5544	$131.55	$131.55	$131.60
Purchase #5	$200.58	11.401%	$223.4481	$223.45	$223.45	$223.40
Purchase #6	$99.58	5.613%	$105.1694	$105.17	$105.15	$105.20
Purchase #7	$77.70	5.611%	$82.0597	$82.06	$82.05	$82.10
7 purchase totals =	$990.70		$1,085.5525	$1,085.56	$1,085.55	$1,085.60