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	$244.83	5.721%	$258.8367	$258.84	$258.85	$258.80
Purchase #2	$94.28	3.483%	$97.5638	$97.56	$97.55	$97.60
Purchase #3	$51.95	4.514%	$54.295	$54.30	$54.30	$54.30
Purchase #4	$6.56	9.259%	$7.1674	$7.17	$7.15	$7.20
Purchase #5	$117.98	11.649%	$131.7235	$131.72	$131.70	$131.70
Purchase #6	$203.49	11.751%	$227.4021	$227.40	$227.40	$227.40
Purchase #7	$154.42	8.480%	$167.5148	$167.51	$167.50	$167.50
7 purchase totals =	$873.51		$944.5033	$944.50	$944.45	$944.50