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	$145.25	5.828%	$153.7152	$153.72	$153.70	$153.70
Purchase #2	$105.28	6.356%	$111.9716	$111.97	$111.95	$112.00
Purchase #3	$147.89	13.495%	$167.8478	$167.85	$167.85	$167.80
Purchase #4	$150.65	3.360%	$155.7118	$155.71	$155.70	$155.70
Purchase #5	$64.30	13.520%	$72.9934	$72.99	$73.00	$73.00
Purchase #6	$213.63	6.386%	$227.2724	$227.27	$227.25	$227.30
Purchase #7	$111.56	6.335%	$118.6273	$118.63	$118.65	$118.60
7 purchase totals =	$938.56		$1,008.1395	$1,008.14	$1,008.10	$1,008.10