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	$181.68	7.236%	$194.8264	$194.83	$194.85	$194.80
Purchase #2	$220.74	4.264%	$230.1524	$230.15	$230.15	$230.20
Purchase #3	$65.67	10.342%	$72.4616	$72.46	$72.45	$72.50
Purchase #4	$96.44	5.271%	$101.5234	$101.52	$101.50	$101.50
Purchase #5	$117.57	4.865%	$123.2898	$123.29	$123.30	$123.30
Purchase #6	$182.61	13.446%	$207.1637	$207.16	$207.15	$207.20
Purchase #7	$165.87	11.640%	$185.1773	$185.18	$185.20	$185.20
7 purchase totals =	$1,030.58		$1,114.5946	$1,114.59	$1,114.60	$1,114.70