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	$179.86	9.445%	$196.8478	$196.85	$196.85	$196.80
Purchase #2	$230.46	9.190%	$251.6393	$251.64	$251.65	$251.60
Purchase #3	$221.79	4.300%	$231.327	$231.33	$231.35	$231.30
Purchase #4	$111.90	3.718%	$116.0604	$116.06	$116.05	$116.10
Purchase #5	$49.70	7.503%	$53.429	$53.43	$53.45	$53.40
Purchase #6	$234.36	12.600%	$263.8894	$263.89	$263.90	$263.90
Purchase #7	$147.87	3.471%	$153.0026	$153.00	$153.00	$153.00
7 purchase totals =	$1,175.94		$1,266.1955	$1,266.20	$1,266.25	$1,266.10