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	$93.32	11.135%	$103.7112	$103.71	$103.70	$103.70
Purchase #2	$17.34	10.299%	$19.1258	$19.13	$19.15	$19.10
Purchase #3	$9.94	3.644%	$10.3022	$10.30	$10.30	$10.30
Purchase #4	$69.34	13.677%	$78.8236	$78.82	$78.80	$78.80
Purchase #5	$199.28	13.439%	$226.0612	$226.06	$226.05	$226.10
Purchase #6	$56.85	6.856%	$60.7476	$60.75	$60.75	$60.70
Purchase #7	$35.93	3.451%	$37.1699	$37.17	$37.15	$37.20
7 purchase totals =	$482.00		$535.9415	$535.94	$535.90	$535.90