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	$210.74	7.693%	$226.9522	$226.95	$226.95	$227.00
Purchase #2	$171.71	5.573%	$181.2794	$181.28	$181.30	$181.30
Purchase #3	$113.37	4.106%	$118.025	$118.03	$118.05	$118.00
Purchase #4	$91.32	10.216%	$100.6493	$100.65	$100.65	$100.60
Purchase #5	$161.59	13.462%	$183.3432	$183.34	$183.35	$183.30
Purchase #6	$180.37	8.794%	$196.2317	$196.23	$196.25	$196.20
Purchase #7	$244.84	4.330%	$255.4416	$255.44	$255.45	$255.40
7 purchase totals =	$1,173.94		$1,261.9224	$1,261.92	$1,262.00	$1,261.80