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	$214.87	10.838%	$238.1576	$238.16	$238.15	$238.20
Purchase #2	$157.85	9.505%	$172.8536	$172.85	$172.85	$172.90
Purchase #3	$80.39	6.466%	$85.588	$85.59	$85.60	$85.60
Purchase #4	$199.41	11.319%	$221.9812	$221.98	$222.00	$222.00
Purchase #5	$102.56	3.261%	$105.9045	$105.90	$105.90	$105.90
Purchase #6	$131.94	10.578%	$145.8966	$145.90	$145.90	$145.90
Purchase #7	$185.90	3.451%	$192.3154	$192.32	$192.30	$192.30
7 purchase totals =	$1,072.92		$1,162.6969	$1,162.70	$1,162.70	$1,162.80