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	$88.43	7.242%	$94.8341	$94.83	$94.85	$94.80
Purchase #2	$103.27	8.331%	$111.8734	$111.87	$111.85	$111.90
Purchase #3	$6.83	4.537%	$7.1399	$7.14	$7.15	$7.10
Purchase #4	$48.25	12.551%	$54.3059	$54.31	$54.30	$54.30
Purchase #5	$68.28	9.612%	$74.8431	$74.84	$74.85	$74.80
Purchase #6	$94.59	13.534%	$107.3918	$107.39	$107.40	$107.40
Purchase #7	$238.40	5.243%	$250.8993	$250.90	$250.90	$250.90
7 purchase totals =	$648.05		$701.2875	$701.28	$701.30	$701.20