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	$191.43	9.608%	$209.8226	$209.82	$209.80	$209.80
Purchase #2	$177.26	10.575%	$196.0052	$196.01	$196.00	$196.00
Purchase #3	$130.69	11.397%	$145.5847	$145.58	$145.60	$145.60
Purchase #4	$243.81	8.493%	$264.5168	$264.52	$264.50	$264.50
Purchase #5	$250.57	5.673%	$264.7848	$264.78	$264.80	$264.80
Purchase #6	$56.27	10.123%	$61.9662	$61.97	$61.95	$62.00
Purchase #7	$118.91	6.138%	$126.2087	$126.21	$126.20	$126.20
7 purchase totals =	$1,168.94		$1,268.8890	$1,268.89	$1,268.85	$1,268.90