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	$201.55	11.635%	$225.0003	$225.00	$225.00	$225.00
Purchase #2	$100.25	11.563%	$111.8419	$111.84	$111.85	$111.80
Purchase #3	$215.67	11.393%	$240.2413	$240.24	$240.25	$240.20
Purchase #4	$194.74	13.437%	$220.9072	$220.91	$220.90	$220.90
Purchase #5	$10.42	4.387%	$10.8771	$10.88	$10.90	$10.90
Purchase #6	$187.72	12.556%	$211.2901	$211.29	$211.30	$211.30
Purchase #7	$193.37	6.230%	$205.417	$205.42	$205.40	$205.40
7 purchase totals =	$1,103.72		$1,225.5749	$1,225.58	$1,225.60	$1,225.50