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	$179.42	9.542%	$196.5403	$196.54	$196.55	$196.50
Purchase #2	$240.78	6.122%	$255.5206	$255.52	$255.50	$255.50
Purchase #3	$89.76	5.588%	$94.7758	$94.78	$94.80	$94.80
Purchase #4	$116.89	6.707%	$124.7298	$124.73	$124.75	$124.70
Purchase #5	$89.32	3.695%	$92.6204	$92.62	$92.60	$92.60
Purchase #6	$237.69	12.423%	$267.2182	$267.22	$267.20	$267.20
Purchase #7	$134.44	7.731%	$144.8336	$144.83	$144.85	$144.80
7 purchase totals =	$1,088.30		$1,176.2387	$1,176.24	$1,176.25	$1,176.10