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	$203.31	5.536%	$214.5652	$214.57	$214.55	$214.60
Purchase #2	$11.56	9.231%	$12.6271	$12.63	$12.65	$12.60
Purchase #3	$168.69	13.427%	$191.34	$191.34	$191.35	$191.30
Purchase #4	$154.78	7.845%	$166.9225	$166.92	$166.90	$166.90
Purchase #5	$206.75	6.677%	$220.5547	$220.55	$220.55	$220.60
Purchase #6	$82.51	11.288%	$91.8237	$91.82	$91.80	$91.80
Purchase #7	$101.91	3.130%	$105.0998	$105.10	$105.10	$105.10
7 purchase totals =	$929.51		$1,002.9330	$1,002.93	$1,002.90	$1,002.90