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	$201.83	9.525%	$221.0543	$221.05	$221.05	$221.10
Purchase #2	$65.30	8.814%	$71.0555	$71.06	$71.05	$71.10
Purchase #3	$111.71	11.778%	$124.8672	$124.87	$124.85	$124.90
Purchase #4	$19.67	4.786%	$20.6114	$20.61	$20.60	$20.60
Purchase #5	$173.30	10.513%	$191.519	$191.52	$191.50	$191.50
Purchase #6	$215.28	9.355%	$235.4194	$235.42	$235.40	$235.40
Purchase #7	$222.49	11.783%	$248.706	$248.71	$248.70	$248.70
7 purchase totals =	$1,009.58		$1,113.2328	$1,113.24	$1,113.15	$1,113.30