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	$110.61	3.553%	$114.54	$114.54	$114.55	$114.50
Purchase #2	$226.39	6.182%	$240.3854	$240.39	$240.40	$240.40
Purchase #3	$164.92	6.104%	$174.9867	$174.99	$175.00	$175.00
Purchase #4	$154.28	4.561%	$161.3167	$161.32	$161.30	$161.30
Purchase #5	$46.76	11.367%	$52.0752	$52.08	$52.10	$52.10
Purchase #6	$183.42	7.194%	$196.6152	$196.62	$196.60	$196.60
Purchase #7	$137.73	10.478%	$152.1613	$152.16	$152.15	$152.20
7 purchase totals =	$1,024.11		$1,092.0805	$1,092.10	$1,092.10	$1,092.10