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	$207.63	5.780%	$219.631	$219.63	$219.65	$219.60
Purchase #2	$66.89	7.152%	$71.674	$71.67	$71.65	$71.70
Purchase #3	$38.79	11.222%	$43.143	$43.14	$43.15	$43.10
Purchase #4	$16.95	4.620%	$17.7331	$17.73	$17.75	$17.70
Purchase #5	$14.37	13.154%	$16.2602	$16.26	$16.25	$16.30
Purchase #6	$99.92	12.144%	$112.0543	$112.05	$112.05	$112.10
Purchase #7	$85.70	5.651%	$90.5429	$90.54	$90.55	$90.50
7 purchase totals =	$530.25		$571.0385	$571.02	$571.05	$571.00