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	$197.97	10.499%	$218.7549	$218.75	$218.75	$218.80
Purchase #2	$11.59	7.541%	$12.464	$12.46	$12.45	$12.50
Purchase #3	$54.46	13.476%	$61.799	$61.80	$61.80	$61.80
Purchase #4	$173.78	3.638%	$180.1021	$180.10	$180.10	$180.10
Purchase #5	$207.46	10.783%	$229.8304	$229.83	$229.85	$229.80
Purchase #6	$129.26	12.513%	$145.4343	$145.43	$145.45	$145.40
Purchase #7	$151.57	4.808%	$158.8575	$158.86	$158.85	$158.90
7 purchase totals =	$926.09		$1,007.2422	$1,007.23	$1,007.25	$1,007.30