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	$209.25	11.167%	$232.6169	$232.62	$232.60	$232.60
Purchase #2	$226.63	7.806%	$244.3207	$244.32	$244.30	$244.30
Purchase #3	$85.88	4.143%	$89.438	$89.44	$89.45	$89.40
Purchase #4	$77.25	4.137%	$80.4458	$80.45	$80.45	$80.40
Purchase #5	$174.92	7.673%	$188.3416	$188.34	$188.35	$188.30
Purchase #6	$157.80	9.353%	$172.559	$172.56	$172.55	$172.60
Purchase #7	$145.52	8.817%	$158.3505	$158.35	$158.35	$158.40
7 purchase totals =	$1,077.25		$1,166.0725	$1,166.08	$1,166.05	$1,166.00