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	$112.38	12.777%	$126.7388	$126.74	$126.75	$126.70
Purchase #2	$173.28	13.496%	$196.6659	$196.67	$196.65	$196.70
Purchase #3	$40.40	12.485%	$45.4439	$45.44	$45.45	$45.40
Purchase #4	$17.32	13.659%	$19.6857	$19.69	$19.70	$19.70
Purchase #5	$85.43	7.781%	$92.0773	$92.08	$92.10	$92.10
Purchase #6	$236.94	11.671%	$264.5933	$264.59	$264.60	$264.60
Purchase #7	$243.56	10.158%	$268.3008	$268.30	$268.30	$268.30
7 purchase totals =	$909.31		$1,013.5057	$1,013.51	$1,013.55	$1,013.50