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	$212.82	3.113%	$219.4451	$219.45	$219.45	$219.40
Purchase #2	$14.42	6.201%	$15.3142	$15.31	$15.30	$15.30
Purchase #3	$57.26	4.528%	$59.8527	$59.85	$59.85	$59.90
Purchase #4	$156.72	3.532%	$162.2554	$162.26	$162.25	$162.30
Purchase #5	$174.99	11.760%	$195.5688	$195.57	$195.55	$195.60
Purchase #6	$97.33	12.200%	$109.2043	$109.20	$109.20	$109.20
Purchase #7	$111.27	10.707%	$123.1837	$123.18	$123.20	$123.20
7 purchase totals =	$824.81		$884.8242	$884.82	$884.80	$884.90