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	$148.59	10.477%	$164.1578	$164.16	$164.15	$164.20
Purchase #2	$159.88	3.255%	$165.0841	$165.08	$165.10	$165.10
Purchase #3	$115.47	10.436%	$127.5204	$127.52	$127.50	$127.50
Purchase #4	$141.26	3.744%	$146.5488	$146.55	$146.55	$146.50
Purchase #5	$83.68	10.442%	$92.4179	$92.42	$92.40	$92.40
Purchase #6	$181.96	10.256%	$200.6218	$200.62	$200.60	$200.60
Purchase #7	$236.91	6.174%	$251.5368	$251.54	$251.55	$251.50
7 purchase totals =	$1,067.75		$1,147.8876	$1,147.89	$1,147.85	$1,147.80