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	$179.67	5.827%	$190.1394	$190.14	$190.15	$190.10
Purchase #2	$113.46	3.140%	$117.0226	$117.02	$117.00	$117.00
Purchase #3	$50.56	5.659%	$53.4212	$53.42	$53.40	$53.40
Purchase #4	$228.35	6.686%	$243.6175	$243.62	$243.60	$243.60
Purchase #5	$229.33	11.553%	$255.8245	$255.82	$255.80	$255.80
Purchase #6	$102.78	11.647%	$114.7508	$114.75	$114.75	$114.80
Purchase #7	$182.42	5.616%	$192.6647	$192.66	$192.65	$192.70
7 purchase totals =	$1,086.57		$1,167.4407	$1,167.43	$1,167.35	$1,167.40