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	$39.73	12.262%	$44.6017	$44.60	$44.60	$44.60
Purchase #2	$19.80	5.674%	$20.9235	$20.92	$20.90	$20.90
Purchase #3	$10.30	5.562%	$10.8729	$10.87	$10.85	$10.90
Purchase #4	$19.52	6.364%	$20.7623	$20.76	$20.75	$20.80
Purchase #5	$84.35	13.756%	$95.9532	$95.95	$95.95	$96.00
Purchase #6	$50.97	7.615%	$54.8514	$54.85	$54.85	$54.90
Purchase #7	$148.66	6.627%	$158.5117	$158.51	$158.50	$158.50
7 purchase totals =	$373.33		$406.4767	$406.46	$406.40	$406.60