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	$184.96	5.121%	$194.4318	$194.43	$194.45	$194.40
Purchase #2	$92.26	4.450%	$96.3656	$96.37	$96.35	$96.40
Purchase #3	$74.68	5.152%	$78.5275	$78.53	$78.55	$78.50
Purchase #4	$53.39	11.634%	$59.6014	$59.60	$59.60	$59.60
Purchase #5	$105.36	7.825%	$113.6044	$113.60	$113.60	$113.60
Purchase #6	$88.43	13.547%	$100.4096	$100.41	$100.40	$100.40
Purchase #7	$151.28	3.857%	$157.1149	$157.11	$157.10	$157.10
7 purchase totals =	$750.36		$800.0552	$800.05	$800.05	$800.00