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	$88.75	8.835%	$96.5911	$96.59	$96.60	$96.60
Purchase #2	$114.72	10.755%	$127.0581	$127.06	$127.05	$127.10
Purchase #3	$156.84	3.429%	$162.218	$162.22	$162.20	$162.20
Purchase #4	$8.27	10.390%	$9.1293	$9.13	$9.15	$9.10
Purchase #5	$210.31	6.265%	$223.4859	$223.49	$223.50	$223.50
Purchase #6	$186.28	12.461%	$209.4924	$209.49	$209.50	$209.50
Purchase #7	$226.51	6.317%	$240.8186	$240.82	$240.80	$240.80
7 purchase totals =	$991.68		$1,068.7934	$1,068.80	$1,068.80	$1,068.80