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	$196.34	13.199%	$222.2549	$222.25	$222.25	$222.30
Purchase #2	$198.90	3.464%	$205.7899	$205.79	$205.80	$205.80
Purchase #3	$5.37	3.262%	$5.5452	$5.55	$5.55	$5.50
Purchase #4	$172.75	7.275%	$185.3176	$185.32	$185.30	$185.30
Purchase #5	$154.73	8.828%	$168.3896	$168.39	$168.40	$168.40
Purchase #6	$99.60	9.396%	$108.9584	$108.96	$108.95	$109.00
Purchase #7	$131.71	13.620%	$149.6489	$149.65	$149.65	$149.60
7 purchase totals =	$959.40		$1,045.9045	$1,045.91	$1,045.90	$1,045.90