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	$202.69	11.432%	$225.8615	$225.86	$225.85	$225.90
Purchase #2	$37.92	4.173%	$39.5024	$39.50	$39.50	$39.50
Purchase #3	$133.64	8.285%	$144.7121	$144.71	$144.70	$144.70
Purchase #4	$245.54	7.762%	$264.5988	$264.60	$264.60	$264.60
Purchase #5	$155.87	6.743%	$166.3803	$166.38	$166.40	$166.40
Purchase #6	$39.63	10.687%	$43.8653	$43.87	$43.85	$43.90
Purchase #7	$233.26	10.463%	$257.666	$257.67	$257.65	$257.70
7 purchase totals =	$1,048.55		$1,142.5864	$1,142.59	$1,142.55	$1,142.70