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	$171.96	4.444%	$179.6019	$179.60	$179.60	$179.60
Purchase #2	$100.99	6.288%	$107.3403	$107.34	$107.35	$107.30
Purchase #3	$38.25	3.776%	$39.6943	$39.69	$39.70	$39.70
Purchase #4	$132.77	7.423%	$142.6255	$142.63	$142.65	$142.60
Purchase #5	$101.89	9.432%	$111.5003	$111.50	$111.50	$111.50
Purchase #6	$183.86	13.817%	$209.2639	$209.26	$209.25	$209.30
Purchase #7	$233.76	3.516%	$241.979	$241.98	$242.00	$242.00
7 purchase totals =	$963.48		$1,032.0052	$1,032.00	$1,032.05	$1,032.00