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	$204.39	5.454%	$215.5374	$215.54	$215.55	$215.50
Purchase #2	$11.77	8.290%	$12.7457	$12.75	$12.75	$12.70
Purchase #3	$97.30	3.412%	$100.6199	$100.62	$100.60	$100.60
Purchase #4	$205.42	6.636%	$219.0517	$219.05	$219.05	$219.10
Purchase #5	$151.54	10.103%	$166.8501	$166.85	$166.85	$166.90
Purchase #6	$62.48	8.241%	$67.629	$67.63	$67.65	$67.60
Purchase #7	$129.41	10.433%	$142.9113	$142.91	$142.90	$142.90
7 purchase totals =	$862.31		$925.3451	$925.35	$925.35	$925.30