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	$112.44	10.161%	$123.865	$123.87	$123.85	$123.90
Purchase #2	$176.32	9.694%	$193.4125	$193.41	$193.40	$193.40
Purchase #3	$55.39	4.303%	$57.7734	$57.77	$57.75	$57.80
Purchase #4	$159.73	7.444%	$171.6203	$171.62	$171.60	$171.60
Purchase #5	$166.97	12.561%	$187.9431	$187.94	$187.95	$187.90
Purchase #6	$178.44	3.655%	$184.962	$184.96	$184.95	$185.00
Purchase #7	$91.66	5.382%	$96.5931	$96.59	$96.60	$96.60
7 purchase totals =	$940.95		$1,016.1694	$1,016.16	$1,016.10	$1,016.20