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	$114.37	3.762%	$118.6726	$118.67	$118.65	$118.70
Purchase #2	$131.96	9.358%	$144.3088	$144.31	$144.30	$144.30
Purchase #3	$175.53	5.633%	$185.4176	$185.42	$185.40	$185.40
Purchase #4	$246.89	13.186%	$279.4449	$279.44	$279.45	$279.40
Purchase #5	$96.93	4.519%	$101.3103	$101.31	$101.30	$101.30
Purchase #6	$135.28	12.260%	$151.8653	$151.87	$151.85	$151.90
Purchase #7	$155.97	9.748%	$171.174	$171.17	$171.15	$171.20
7 purchase totals =	$1,056.93		$1,152.1935	$1,152.19	$1,152.10	$1,152.20