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	$95.33	13.447%	$108.149	$108.15	$108.15	$108.10
Purchase #2	$120.42	12.217%	$135.1317	$135.13	$135.15	$135.10
Purchase #3	$240.26	6.180%	$255.1081	$255.11	$255.10	$255.10
Purchase #4	$162.92	6.493%	$173.4984	$173.50	$173.50	$173.50
Purchase #5	$203.47	13.596%	$231.1338	$231.13	$231.15	$231.10
Purchase #6	$50.85	8.607%	$55.2267	$55.23	$55.25	$55.20
Purchase #7	$55.76	9.482%	$61.0472	$61.05	$61.05	$61.00
7 purchase totals =	$929.01		$1,019.2949	$1,019.30	$1,019.35	$1,019.10