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	$147.59	13.703%	$167.8143	$167.81	$167.80	$167.80
Purchase #2	$70.70	5.183%	$74.3644	$74.36	$74.35	$74.40
Purchase #3	$162.43	5.795%	$171.8428	$171.84	$171.85	$171.80
Purchase #4	$149.33	4.147%	$155.5227	$155.52	$155.50	$155.50
Purchase #5	$104.54	10.855%	$115.8878	$115.89	$115.90	$115.90
Purchase #6	$195.38	8.739%	$212.4543	$212.45	$212.45	$212.50
Purchase #7	$104.50	13.208%	$118.3024	$118.30	$118.30	$118.30
7 purchase totals =	$934.47		$1,016.1887	$1,016.17	$1,016.15	$1,016.20