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	$167.95	4.234%	$175.061	$175.06	$175.05	$175.10
Purchase #2	$31.92	8.804%	$34.7302	$34.73	$34.75	$34.70
Purchase #3	$9.77	4.841%	$10.243	$10.24	$10.25	$10.20
Purchase #4	$129.40	11.465%	$144.2357	$144.24	$144.25	$144.20
Purchase #5	$111.72	8.199%	$120.8799	$120.88	$120.90	$120.90
Purchase #6	$105.31	5.835%	$111.4548	$111.45	$111.45	$111.50
Purchase #7	$149.40	11.145%	$166.0506	$166.05	$166.05	$166.10
7 purchase totals =	$705.47		$762.6552	$762.65	$762.70	$762.70