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	$73.97	3.263%	$76.3836	$76.38	$76.40	$76.40
Purchase #2	$74.78	4.483%	$78.1324	$78.13	$78.15	$78.10
Purchase #3	$174.79	10.370%	$192.9157	$192.92	$192.90	$192.90
Purchase #4	$60.52	11.382%	$67.4084	$67.41	$67.40	$67.40
Purchase #5	$145.63	4.351%	$151.9664	$151.97	$151.95	$152.00
Purchase #6	$92.69	8.587%	$100.6493	$100.65	$100.65	$100.60
Purchase #7	$58.88	10.725%	$65.1949	$65.19	$65.20	$65.20
7 purchase totals =	$681.26		$732.6507	$732.65	$732.65	$732.60