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	$62.29	4.785%	$65.2706	$65.27	$65.25	$65.30
Purchase #2	$71.37	12.527%	$80.3105	$80.31	$80.30	$80.30
Purchase #3	$211.79	5.666%	$223.79	$223.79	$223.80	$223.80
Purchase #4	$90.75	8.338%	$98.3167	$98.32	$98.30	$98.30
Purchase #5	$237.47	6.326%	$252.4924	$252.49	$252.50	$252.50
Purchase #6	$134.56	7.805%	$145.0624	$145.06	$145.05	$145.10
Purchase #7	$175.81	3.839%	$182.5593	$182.56	$182.55	$182.60
7 purchase totals =	$984.04		$1,047.8019	$1,047.80	$1,047.75	$1,047.90