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	$205.48	10.796%	$227.6636	$227.66	$227.65	$227.70
Purchase #2	$146.42	11.139%	$162.7297	$162.73	$162.75	$162.70
Purchase #3	$159.91	5.137%	$168.1246	$168.12	$168.10	$168.10
Purchase #4	$38.89	3.114%	$40.101	$40.10	$40.10	$40.10
Purchase #5	$55.93	11.273%	$62.235	$62.24	$62.25	$62.20
Purchase #6	$221.39	10.271%	$244.129	$244.13	$244.15	$244.10
Purchase #7	$48.51	9.611%	$53.1723	$53.17	$53.15	$53.20
7 purchase totals =	$876.53		$958.1552	$958.15	$958.15	$958.10