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	$208.77	9.320%	$228.2274	$228.23	$228.25	$228.20
Purchase #2	$173.27	6.468%	$184.4771	$184.48	$184.50	$184.50
Purchase #3	$73.46	12.772%	$82.8423	$82.84	$82.85	$82.80
Purchase #4	$52.44	5.775%	$55.4684	$55.47	$55.45	$55.50
Purchase #5	$216.86	11.623%	$242.0656	$242.07	$242.05	$242.10
Purchase #6	$221.75	3.458%	$229.4181	$229.42	$229.40	$229.40
Purchase #7	$60.54	9.142%	$66.0746	$66.07	$66.05	$66.10
7 purchase totals =	$1,007.09		$1,088.5735	$1,088.58	$1,088.55	$1,088.60