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	$120.92	9.546%	$132.463	$132.46	$132.45	$132.50
Purchase #2	$67.30	7.450%	$72.3139	$72.31	$72.30	$72.30
Purchase #3	$150.61	3.290%	$155.5651	$155.57	$155.55	$155.60
Purchase #4	$109.40	3.389%	$113.1076	$113.11	$113.10	$113.10
Purchase #5	$193.73	11.353%	$215.7242	$215.72	$215.70	$215.70
Purchase #6	$230.45	12.520%	$259.3023	$259.30	$259.30	$259.30
Purchase #7	$106.62	5.765%	$112.7666	$112.77	$112.75	$112.80
7 purchase totals =	$979.03		$1,061.2427	$1,061.24	$1,061.15	$1,061.30