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	$165.78	9.223%	$181.0699	$181.07	$181.05	$181.10
Purchase #2	$100.75	10.403%	$111.231	$111.23	$111.25	$111.20
Purchase #3	$92.84	7.535%	$99.8355	$99.84	$99.85	$99.80
Purchase #4	$115.56	5.400%	$121.8002	$121.80	$121.80	$121.80
Purchase #5	$218.38	11.749%	$244.0375	$244.04	$244.05	$244.00
Purchase #6	$152.99	13.499%	$173.6421	$173.64	$173.65	$173.60
Purchase #7	$102.29	10.131%	$112.653	$112.65	$112.65	$112.70
7 purchase totals =	$948.59		$1,044.2692	$1,044.27	$1,044.30	$1,044.20