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	$61.92	4.630%	$64.7869	$64.79	$64.80	$64.80
Purchase #2	$204.37	5.742%	$216.1049	$216.10	$216.10	$216.10
Purchase #3	$202.86	10.213%	$223.5781	$223.58	$223.60	$223.60
Purchase #4	$53.52	6.273%	$56.8773	$56.88	$56.90	$56.90
Purchase #5	$157.71	4.353%	$164.5751	$164.58	$164.60	$164.60
Purchase #6	$54.40	9.607%	$59.6262	$59.63	$59.65	$59.60
Purchase #7	$192.34	11.519%	$214.4956	$214.50	$214.50	$214.50
7 purchase totals =	$927.12		$1,000.0441	$1,000.06	$1,000.15	$1,000.10