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	$181.27	7.763%	$195.342	$195.34	$195.35	$195.30
Purchase #2	$193.77	9.730%	$212.6238	$212.62	$212.60	$212.60
Purchase #3	$53.65	5.231%	$56.4564	$56.46	$56.45	$56.50
Purchase #4	$98.91	4.743%	$103.6013	$103.60	$103.60	$103.60
Purchase #5	$55.84	7.194%	$59.8571	$59.86	$59.85	$59.90
Purchase #6	$242.41	13.742%	$275.722	$275.72	$275.70	$275.70
Purchase #7	$137.29	13.318%	$155.5743	$155.57	$155.55	$155.60
7 purchase totals =	$963.14		$1,059.1769	$1,059.17	$1,059.10	$1,059.20