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	$124.65	5.215%	$131.1505	$131.15	$131.15	$131.20
Purchase #2	$113.39	5.215%	$119.3033	$119.30	$119.30	$119.30
Purchase #3	$133.70	7.727%	$144.031	$144.03	$144.05	$144.00
Purchase #4	$108.73	13.552%	$123.4651	$123.47	$123.45	$123.50
Purchase #5	$168.93	3.665%	$175.1213	$175.12	$175.10	$175.10
Purchase #6	$111.80	4.106%	$116.3905	$116.39	$116.40	$116.40
Purchase #7	$198.71	13.721%	$225.975	$225.98	$226.00	$226.00
7 purchase totals =	$959.91		$1,035.4367	$1,035.44	$1,035.45	$1,035.50