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	$214.42	7.572%	$230.6559	$230.66	$230.65	$230.70
Purchase #2	$156.51	8.550%	$169.8916	$169.89	$169.90	$169.90
Purchase #3	$88.54	8.560%	$96.119	$96.12	$96.10	$96.10
Purchase #4	$234.75	10.182%	$258.6522	$258.65	$258.65	$258.70
Purchase #5	$207.46	7.181%	$222.3577	$222.36	$222.35	$222.40
Purchase #6	$33.25	13.463%	$37.7264	$37.73	$37.75	$37.70
Purchase #7	$163.38	5.838%	$172.9181	$172.92	$172.90	$172.90
7 purchase totals =	$1,098.31		$1,188.3209	$1,188.33	$1,188.30	$1,188.40