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	$163.31	7.743%	$175.9551	$175.96	$175.95	$176.00
Purchase #2	$105.25	9.627%	$115.3824	$115.38	$115.40	$115.40
Purchase #3	$49.77	8.754%	$54.1269	$54.13	$54.15	$54.10
Purchase #4	$83.61	9.383%	$91.4551	$91.46	$91.45	$91.50
Purchase #5	$204.95	10.812%	$227.1092	$227.11	$227.10	$227.10
Purchase #6	$100.71	11.154%	$111.9432	$111.94	$111.95	$111.90
Purchase #7	$230.85	4.312%	$240.8043	$240.80	$240.80	$240.80
7 purchase totals =	$938.45		$1,016.7762	$1,016.78	$1,016.80	$1,016.80