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	$194.90	10.855%	$216.0564	$216.06	$216.05	$216.10
Purchase #2	$9.56	9.374%	$10.4562	$10.46	$10.45	$10.50
Purchase #3	$81.34	6.582%	$86.6938	$86.69	$86.70	$86.70
Purchase #4	$19.50	13.603%	$22.1526	$22.15	$22.15	$22.20
Purchase #5	$59.60	3.122%	$61.4607	$61.46	$61.45	$61.50
Purchase #6	$58.76	4.829%	$61.5975	$61.60	$61.60	$61.60
Purchase #7	$248.69	12.227%	$279.0973	$279.10	$279.10	$279.10
7 purchase totals =	$672.35		$737.5145	$737.52	$737.50	$737.70