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	$69.58	4.269%	$72.5504	$72.55	$72.55	$72.60
Purchase #2	$171.85	12.273%	$192.9412	$192.94	$192.95	$192.90
Purchase #3	$222.27	12.697%	$250.4916	$250.49	$250.50	$250.50
Purchase #4	$194.92	6.568%	$207.7223	$207.72	$207.70	$207.70
Purchase #5	$30.30	7.391%	$32.5395	$32.54	$32.55	$32.50
Purchase #6	$50.59	7.648%	$54.4591	$54.46	$54.45	$54.50
Purchase #7	$244.26	11.447%	$272.2204	$272.22	$272.20	$272.20
7 purchase totals =	$983.77		$1,082.9245	$1,082.92	$1,082.90	$1,082.90