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	$185.25	5.723%	$195.8519	$195.85	$195.85	$195.90
Purchase #2	$111.26	3.555%	$115.2153	$115.22	$115.20	$115.20
Purchase #3	$33.84	12.539%	$38.0832	$38.08	$38.10	$38.10
Purchase #4	$178.53	7.484%	$191.8912	$191.89	$191.90	$191.90
Purchase #5	$47.78	13.707%	$54.3292	$54.33	$54.35	$54.30
Purchase #6	$195.29	5.695%	$206.4118	$206.41	$206.40	$206.40
Purchase #7	$228.47	13.152%	$258.5184	$258.52	$258.50	$258.50
7 purchase totals =	$980.42		$1,060.3010	$1,060.30	$1,060.30	$1,060.30