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	$42.72	7.395%	$45.8791	$45.88	$45.90	$45.90
Purchase #2	$12.41	11.653%	$13.8561	$13.86	$13.85	$13.90
Purchase #3	$244.30	10.272%	$269.3945	$269.39	$269.40	$269.40
Purchase #4	$127.35	11.681%	$142.2258	$142.23	$142.25	$142.20
Purchase #5	$155.49	11.681%	$173.6528	$173.65	$173.65	$173.70
Purchase #6	$116.51	10.523%	$128.7703	$128.77	$128.75	$128.80
Purchase #7	$248.44	10.130%	$273.607	$273.61	$273.60	$273.60
7 purchase totals =	$947.22		$1,047.3856	$1,047.39	$1,047.40	$1,047.50