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	$140.87	3.406%	$145.668	$145.67	$145.65	$145.70
Purchase #2	$44.44	4.847%	$46.594	$46.59	$46.60	$46.60
Purchase #3	$152.95	8.756%	$166.3423	$166.34	$166.35	$166.30
Purchase #4	$87.41	3.802%	$90.7333	$90.73	$90.75	$90.70
Purchase #5	$104.51	4.713%	$109.4356	$109.44	$109.45	$109.40
Purchase #6	$218.52	10.505%	$241.4755	$241.48	$241.50	$241.50
Purchase #7	$193.31	11.716%	$215.9582	$215.96	$215.95	$216.00
7 purchase totals =	$942.01		$1,016.2069	$1,016.21	$1,016.25	$1,016.20