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	$67.83	12.219%	$76.1181	$76.12	$76.10	$76.10
Purchase #2	$37.98	13.575%	$43.1358	$43.14	$43.15	$43.10
Purchase #3	$20.74	4.196%	$21.6103	$21.61	$21.60	$21.60
Purchase #4	$156.83	3.786%	$162.7676	$162.77	$162.75	$162.80
Purchase #5	$7.64	4.379%	$7.9746	$7.97	$7.95	$8.00
Purchase #6	$165.78	10.429%	$183.0692	$183.07	$183.05	$183.10
Purchase #7	$212.56	5.209%	$223.6323	$223.63	$223.65	$223.60
7 purchase totals =	$669.36		$718.3079	$718.31	$718.25	$718.30