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	$154.26	7.520%	$165.8604	$165.86	$165.85	$165.90
Purchase #2	$98.57	10.702%	$109.119	$109.12	$109.10	$109.10
Purchase #3	$130.71	10.621%	$144.5927	$144.59	$144.60	$144.60
Purchase #4	$136.74	12.262%	$153.5071	$153.51	$153.50	$153.50
Purchase #5	$236.29	6.570%	$251.8143	$251.81	$251.80	$251.80
Purchase #6	$131.75	9.840%	$144.7142	$144.71	$144.70	$144.70
Purchase #7	$40.42	12.330%	$45.4038	$45.40	$45.40	$45.40
7 purchase totals =	$928.74		$1,015.0115	$1,015.00	$1,014.95	$1,015.00