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	$48.98	6.618%	$52.2215	$52.22	$52.20	$52.20
Purchase #2	$86.34	10.550%	$95.4489	$95.45	$95.45	$95.40
Purchase #3	$26.88	3.156%	$27.7283	$27.73	$27.75	$27.70
Purchase #4	$63.51	6.587%	$67.6934	$67.69	$67.70	$67.70
Purchase #5	$37.41	12.332%	$42.0234	$42.02	$42.00	$42.00
Purchase #6	$47.39	3.528%	$49.0619	$49.06	$49.05	$49.10
Purchase #7	$47.94	11.252%	$53.3342	$53.33	$53.35	$53.30
7 purchase totals =	$358.45		$387.5116	$387.50	$387.50	$387.40