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	$219.36	11.605%	$244.8167	$244.82	$244.80	$244.80
Purchase #2	$133.37	11.819%	$149.133	$149.13	$149.15	$149.10
Purchase #3	$101.47	13.139%	$114.8021	$114.80	$114.80	$114.80
Purchase #4	$35.85	4.842%	$37.5859	$37.59	$37.60	$37.60
Purchase #5	$232.32	4.731%	$243.3111	$243.31	$243.30	$243.30
Purchase #6	$140.88	3.243%	$145.4487	$145.45	$145.45	$145.40
Purchase #7	$123.86	10.693%	$137.1043	$137.10	$137.10	$137.10
7 purchase totals =	$987.11		$1,072.2018	$1,072.20	$1,072.20	$1,072.10