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	$142.42	7.109%	$152.5446	$152.54	$152.55	$152.50
Purchase #2	$75.31	7.181%	$80.718	$80.72	$80.70	$80.70
Purchase #3	$81.60	10.132%	$89.8677	$89.87	$89.85	$89.90
Purchase #4	$134.66	8.239%	$145.7546	$145.75	$145.75	$145.80
Purchase #5	$173.32	12.494%	$194.9746	$194.97	$194.95	$195.00
Purchase #6	$226.60	3.624%	$234.812	$234.81	$234.80	$234.80
Purchase #7	$164.51	8.302%	$178.1676	$178.17	$178.15	$178.20
7 purchase totals =	$998.42		$1,076.8391	$1,076.83	$1,076.75	$1,076.90