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	$106.84	4.761%	$111.9267	$111.93	$111.95	$111.90
Purchase #2	$29.28	13.211%	$33.1482	$33.15	$33.15	$33.10
Purchase #3	$31.96	9.688%	$35.0563	$35.06	$35.05	$35.10
Purchase #4	$78.70	8.758%	$85.5925	$85.59	$85.60	$85.60
Purchase #5	$25.81	7.487%	$27.7424	$27.74	$27.75	$27.70
Purchase #6	$52.26	9.663%	$57.3099	$57.31	$57.30	$57.30
Purchase #7	$117.27	4.696%	$122.777	$122.78	$122.80	$122.80
7 purchase totals =	$442.12		$473.5530	$473.56	$473.60	$473.50