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	$63.63	13.371%	$72.138	$72.14	$72.15	$72.10
Purchase #2	$122.72	3.566%	$127.0962	$127.10	$127.10	$127.10
Purchase #3	$57.26	12.524%	$64.4312	$64.43	$64.45	$64.40
Purchase #4	$173.97	3.540%	$180.1285	$180.13	$180.15	$180.10
Purchase #5	$249.60	6.812%	$266.6028	$266.60	$266.60	$266.60
Purchase #6	$110.50	12.321%	$124.1147	$124.11	$124.10	$124.10
Purchase #7	$161.61	10.820%	$179.0962	$179.10	$179.10	$179.10
7 purchase totals =	$939.29		$1,013.6076	$1,013.61	$1,013.65	$1,013.50