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	$245.54	4.156%	$255.7446	$255.74	$255.75	$255.70
Purchase #2	$96.41	4.679%	$100.921	$100.92	$100.90	$100.90
Purchase #3	$199.34	3.111%	$205.5415	$205.54	$205.55	$205.50
Purchase #4	$49.65	4.572%	$51.92	$51.92	$51.90	$51.90
Purchase #5	$245.46	5.179%	$258.1724	$258.17	$258.15	$258.20
Purchase #6	$40.66	13.144%	$46.0044	$46.00	$46.00	$46.00
Purchase #7	$80.28	11.489%	$89.5034	$89.50	$89.50	$89.50
7 purchase totals =	$957.34		$1,007.8073	$1,007.79	$1,007.75	$1,007.70