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	$60.42	5.582%	$63.7926	$63.79	$63.80	$63.80
Purchase #2	$156.51	12.295%	$175.7529	$175.75	$175.75	$175.80
Purchase #3	$227.50	12.709%	$256.413	$256.41	$256.40	$256.40
Purchase #4	$105.70	5.141%	$111.134	$111.13	$111.15	$111.10
Purchase #5	$114.92	11.192%	$127.7818	$127.78	$127.80	$127.80
Purchase #6	$147.56	7.351%	$158.4071	$158.41	$158.40	$158.40
Purchase #7	$185.57	9.121%	$202.4958	$202.50	$202.50	$202.50
7 purchase totals =	$998.18		$1,095.7772	$1,095.77	$1,095.80	$1,095.80