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	$174.31	4.348%	$181.889	$181.89	$181.90	$181.90
Purchase #2	$132.51	11.784%	$148.125	$148.13	$148.15	$148.10
Purchase #3	$117.86	8.266%	$127.6023	$127.60	$127.60	$127.60
Purchase #4	$149.55	4.155%	$155.7638	$155.76	$155.75	$155.80
Purchase #5	$75.30	4.427%	$78.6335	$78.63	$78.65	$78.60
Purchase #6	$75.61	5.519%	$79.7829	$79.78	$79.80	$79.80
Purchase #7	$167.73	4.157%	$174.7025	$174.70	$174.70	$174.70
7 purchase totals =	$892.87		$946.4990	$946.49	$946.55	$946.50