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	$131.67	8.394%	$142.7224	$142.72	$142.70	$142.70
Purchase #2	$52.83	3.191%	$54.5158	$54.52	$54.50	$54.50
Purchase #3	$141.66	7.498%	$152.2817	$152.28	$152.30	$152.30
Purchase #4	$104.49	8.333%	$113.1972	$113.20	$113.20	$113.20
Purchase #5	$214.51	9.511%	$234.912	$234.91	$234.90	$234.90
Purchase #6	$159.95	13.536%	$181.6008	$181.60	$181.60	$181.60
Purchase #7	$153.94	7.437%	$165.3885	$165.39	$165.40	$165.40
7 purchase totals =	$959.05		$1,044.6184	$1,044.62	$1,044.60	$1,044.60