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	$175.40	5.699%	$185.396	$185.40	$185.40	$185.40
Purchase #2	$205.60	5.130%	$216.1473	$216.15	$216.15	$216.10
Purchase #3	$134.28	13.839%	$152.863	$152.86	$152.85	$152.90
Purchase #4	$146.93	9.440%	$160.8002	$160.80	$160.80	$160.80
Purchase #5	$39.78	13.377%	$45.1014	$45.10	$45.10	$45.10
Purchase #6	$145.46	4.180%	$151.5402	$151.54	$151.55	$151.50
Purchase #7	$115.82	4.822%	$121.4048	$121.40	$121.40	$121.40
7 purchase totals =	$963.27		$1,033.2529	$1,033.25	$1,033.25	$1,033.20