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	$241.32	3.155%	$248.9336	$248.93	$248.95	$248.90
Purchase #2	$8.93	13.687%	$10.1522	$10.15	$10.15	$10.20
Purchase #3	$92.32	9.172%	$100.7876	$100.79	$100.80	$100.80
Purchase #4	$66.45	8.736%	$72.2551	$72.26	$72.25	$72.30
Purchase #5	$244.73	7.778%	$263.7651	$263.77	$263.75	$263.80
Purchase #6	$221.73	6.725%	$236.6413	$236.64	$236.65	$236.60
Purchase #7	$130.46	3.144%	$134.5617	$134.56	$134.55	$134.60
7 purchase totals =	$1,005.94		$1,067.0966	$1,067.10	$1,067.10	$1,067.20