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	$232.52	9.524%	$254.6652	$254.67	$254.65	$254.70
Purchase #2	$156.61	10.254%	$172.6688	$172.67	$172.65	$172.70
Purchase #3	$164.77	12.422%	$185.2377	$185.24	$185.25	$185.20
Purchase #4	$23.28	13.832%	$26.5001	$26.50	$26.50	$26.50
Purchase #5	$198.55	11.620%	$221.6215	$221.62	$221.60	$221.60
Purchase #6	$145.77	6.728%	$155.5774	$155.58	$155.60	$155.60
Purchase #7	$28.28	4.717%	$29.614	$29.61	$29.60	$29.60
7 purchase totals =	$949.78		$1,045.8847	$1,045.89	$1,045.85	$1,045.90