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	$212.39	10.185%	$234.0219	$234.02	$234.00	$234.00
Purchase #2	$52.52	4.545%	$54.907	$54.91	$54.90	$54.90
Purchase #3	$246.48	3.575%	$255.2917	$255.29	$255.30	$255.30
Purchase #4	$173.77	12.870%	$196.1342	$196.13	$196.15	$196.10
Purchase #5	$182.40	4.301%	$190.245	$190.25	$190.25	$190.20
Purchase #6	$83.84	3.206%	$86.5279	$86.53	$86.55	$86.50
Purchase #7	$72.39	11.517%	$80.7272	$80.73	$80.75	$80.70
7 purchase totals =	$1,023.79		$1,097.8549	$1,097.86	$1,097.90	$1,097.70