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	$84.25	13.522%	$95.6423	$95.64	$95.65	$95.60
Purchase #2	$123.73	7.573%	$133.1001	$133.10	$133.10	$133.10
Purchase #3	$219.79	7.294%	$235.8215	$235.82	$235.80	$235.80
Purchase #4	$184.47	7.388%	$198.0986	$198.10	$198.10	$198.10
Purchase #5	$98.98	12.489%	$111.3416	$111.34	$111.35	$111.30
Purchase #6	$30.58	6.154%	$32.4619	$32.46	$32.45	$32.50
Purchase #7	$141.77	13.364%	$160.7161	$160.72	$160.70	$160.70
7 purchase totals =	$883.57		$967.1821	$967.18	$967.15	$967.10