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	$213.71	9.359%	$233.7111	$233.71	$233.70	$233.70
Purchase #2	$164.86	9.867%	$181.1267	$181.13	$181.15	$181.10
Purchase #3	$178.84	3.856%	$185.7361	$185.74	$185.75	$185.70
Purchase #4	$96.36	9.379%	$105.3976	$105.40	$105.40	$105.40
Purchase #5	$29.65	7.284%	$31.8097	$31.81	$31.80	$31.80
Purchase #6	$193.46	11.279%	$215.2804	$215.28	$215.30	$215.30
Purchase #7	$187.72	4.493%	$196.1543	$196.15	$196.15	$196.20
7 purchase totals =	$1,064.60		$1,149.2159	$1,149.22	$1,149.25	$1,149.20