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	$61.28	9.855%	$67.3191	$67.32	$67.30	$67.30
Purchase #2	$202.51	9.859%	$222.4755	$222.48	$222.50	$222.50
Purchase #3	$98.86	5.837%	$104.6305	$104.63	$104.65	$104.60
Purchase #4	$143.85	5.183%	$151.3057	$151.31	$151.30	$151.30
Purchase #5	$178.56	4.245%	$186.1399	$186.14	$186.15	$186.10
Purchase #6	$230.28	12.697%	$259.5187	$259.52	$259.50	$259.50
Purchase #7	$105.45	6.446%	$112.2473	$112.25	$112.25	$112.20
7 purchase totals =	$1,020.79		$1,103.6367	$1,103.65	$1,103.65	$1,103.50