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	$58.45	4.490%	$61.0744	$61.07	$61.05	$61.10
Purchase #2	$37.62	10.732%	$41.6574	$41.66	$41.65	$41.70
Purchase #3	$195.42	5.268%	$205.7147	$205.71	$205.70	$205.70
Purchase #4	$107.50	13.142%	$121.6277	$121.63	$121.65	$121.60
Purchase #5	$142.96	13.803%	$162.6928	$162.69	$162.70	$162.70
Purchase #6	$85.91	3.343%	$88.782	$88.78	$88.80	$88.80
Purchase #7	$180.86	8.711%	$196.6147	$196.61	$196.60	$196.60
7 purchase totals =	$808.72		$878.1637	$878.15	$878.15	$878.20