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	$12.85	12.475%	$14.453	$14.45	$14.45	$14.50
Purchase #2	$31.94	3.547%	$33.0729	$33.07	$33.05	$33.10
Purchase #3	$196.61	6.369%	$209.1321	$209.13	$209.15	$209.10
Purchase #4	$96.57	10.113%	$106.3361	$106.34	$106.35	$106.30
Purchase #5	$114.37	11.238%	$127.2229	$127.22	$127.20	$127.20
Purchase #6	$35.61	9.387%	$38.9527	$38.95	$38.95	$39.00
Purchase #7	$31.44	3.775%	$32.6269	$32.63	$32.65	$32.60
7 purchase totals =	$519.39		$561.7966	$561.79	$561.80	$561.80