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	$69.46	4.424%	$72.5329	$72.53	$72.55	$72.50
Purchase #2	$216.42	3.609%	$224.2306	$224.23	$224.25	$224.20
Purchase #3	$162.37	11.553%	$181.1286	$181.13	$181.15	$181.10
Purchase #4	$193.89	12.258%	$217.657	$217.66	$217.65	$217.70
Purchase #5	$183.62	4.830%	$192.4888	$192.49	$192.50	$192.50
Purchase #6	$196.70	11.154%	$218.6399	$218.64	$218.65	$218.60
Purchase #7	$60.52	9.121%	$66.04	$66.04	$66.05	$66.00
7 purchase totals =	$1,082.98		$1,172.7178	$1,172.72	$1,172.80	$1,172.60