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	$42.26	8.545%	$45.8711	$45.87	$45.85	$45.90
Purchase #2	$46.40	13.368%	$52.6028	$52.60	$52.60	$52.60
Purchase #3	$150.62	10.673%	$166.6957	$166.70	$166.70	$166.70
Purchase #4	$153.57	13.751%	$174.6874	$174.69	$174.70	$174.70
Purchase #5	$250.45	13.675%	$284.699	$284.70	$284.70	$284.70
Purchase #6	$206.61	3.708%	$214.2711	$214.27	$214.25	$214.30
Purchase #7	$205.36	8.865%	$223.5652	$223.57	$223.55	$223.60
7 purchase totals =	$1,055.27		$1,162.3923	$1,162.40	$1,162.35	$1,162.50