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	$180.70	9.501%	$197.8683	$197.87	$197.85	$197.90
Purchase #2	$197.85	5.705%	$209.1373	$209.14	$209.15	$209.10
Purchase #3	$185.72	5.697%	$196.3005	$196.30	$196.30	$196.30
Purchase #4	$134.85	9.631%	$147.8374	$147.84	$147.85	$147.80
Purchase #5	$92.83	9.453%	$101.6052	$101.61	$101.60	$101.60
Purchase #6	$88.34	13.323%	$100.1095	$100.11	$100.10	$100.10
Purchase #7	$204.94	8.726%	$222.8231	$222.82	$222.80	$222.80
7 purchase totals =	$1,085.23		$1,175.6813	$1,175.69	$1,175.65	$1,175.60