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	$114.57	11.267%	$127.4786	$127.48	$127.50	$127.50
Purchase #2	$110.78	4.345%	$115.5934	$115.59	$115.60	$115.60
Purchase #3	$131.95	12.235%	$148.0941	$148.09	$148.10	$148.10
Purchase #4	$147.69	11.218%	$164.2579	$164.26	$164.25	$164.30
Purchase #5	$222.70	4.302%	$232.2806	$232.28	$232.30	$232.30
Purchase #6	$225.68	11.539%	$251.7212	$251.72	$251.70	$251.70
Purchase #7	$19.90	12.159%	$22.3196	$22.32	$22.30	$22.30
7 purchase totals =	$973.27		$1,061.7454	$1,061.74	$1,061.75	$1,061.80