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	$194.83	11.447%	$217.1322	$217.13	$217.15	$217.10
Purchase #2	$82.91	12.288%	$93.098	$93.10	$93.10	$93.10
Purchase #3	$172.37	10.569%	$190.5878	$190.59	$190.60	$190.60
Purchase #4	$176.55	13.273%	$199.9835	$199.98	$200.00	$200.00
Purchase #5	$67.58	5.397%	$71.2273	$71.23	$71.25	$71.20
Purchase #6	$129.31	10.386%	$142.7401	$142.74	$142.75	$142.70
Purchase #7	$235.98	6.215%	$250.6462	$250.65	$250.65	$250.60
7 purchase totals =	$1,059.53		$1,165.4151	$1,165.42	$1,165.50	$1,165.30