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	$157.50	11.594%	$175.7606	$175.76	$175.75	$175.80
Purchase #2	$53.88	6.379%	$57.317	$57.32	$57.30	$57.30
Purchase #3	$34.73	7.852%	$37.457	$37.46	$37.45	$37.50
Purchase #4	$52.41	5.274%	$55.1741	$55.17	$55.15	$55.20
Purchase #5	$197.79	12.641%	$222.7926	$222.79	$222.80	$222.80
Purchase #6	$190.81	11.526%	$212.8028	$212.80	$212.80	$212.80
Purchase #7	$239.65	5.403%	$252.5983	$252.60	$252.60	$252.60
7 purchase totals =	$926.77		$1,013.9024	$1,013.90	$1,013.85	$1,014.00