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	$217.43	11.555%	$242.554	$242.55	$242.55	$242.60
Purchase #2	$17.43	9.498%	$19.0855	$19.09	$19.10	$19.10
Purchase #3	$53.43	7.714%	$57.5516	$57.55	$57.55	$57.60
Purchase #4	$238.55	8.662%	$259.2132	$259.21	$259.20	$259.20
Purchase #5	$83.57	8.399%	$90.589	$90.59	$90.60	$90.60
Purchase #6	$39.91	6.112%	$42.3493	$42.35	$42.35	$42.30
Purchase #7	$48.83	10.504%	$53.9591	$53.96	$53.95	$54.00
7 purchase totals =	$699.15		$765.3017	$765.30	$765.30	$765.40