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	$42.94	7.464%	$46.145	$46.15	$46.15	$46.10
Purchase #2	$221.58	7.524%	$238.2517	$238.25	$238.25	$238.30
Purchase #3	$96.34	4.691%	$100.8593	$100.86	$100.85	$100.90
Purchase #4	$72.28	13.250%	$81.8571	$81.86	$81.85	$81.90
Purchase #5	$117.46	8.452%	$127.3877	$127.39	$127.40	$127.40
Purchase #6	$79.46	6.653%	$84.7465	$84.75	$84.75	$84.70
Purchase #7	$183.79	5.586%	$194.0565	$194.06	$194.05	$194.10
7 purchase totals =	$813.85		$873.3038	$873.32	$873.30	$873.40