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	$205.57	4.349%	$214.5102	$214.51	$214.50	$214.50
Purchase #2	$68.85	13.767%	$78.3286	$78.33	$78.35	$78.30
Purchase #3	$250.66	13.153%	$283.6293	$283.63	$283.65	$283.60
Purchase #4	$5.33	7.525%	$5.7311	$5.73	$5.75	$5.70
Purchase #5	$132.76	13.607%	$150.8247	$150.82	$150.80	$150.80
Purchase #6	$130.47	10.860%	$144.639	$144.64	$144.65	$144.60
Purchase #7	$204.53	13.396%	$231.9288	$231.93	$231.95	$231.90
7 purchase totals =	$998.17		$1,109.5917	$1,109.59	$1,109.65	$1,109.40