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	$103.60	5.287%	$109.0773	$109.08	$109.10	$109.10
Purchase #2	$160.58	4.591%	$167.9522	$167.95	$167.95	$168.00
Purchase #3	$235.72	7.121%	$252.5056	$252.51	$252.50	$252.50
Purchase #4	$102.38	8.552%	$111.1355	$111.14	$111.15	$111.10
Purchase #5	$178.62	8.162%	$193.199	$193.20	$193.20	$193.20
Purchase #6	$94.41	5.187%	$99.307	$99.31	$99.30	$99.30
Purchase #7	$166.56	3.446%	$172.2997	$172.30	$172.30	$172.30
7 purchase totals =	$1,041.87		$1,105.4763	$1,105.49	$1,105.50	$1,105.50