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	$117.42	8.671%	$127.6015	$127.60	$127.60	$127.60
Purchase #2	$10.28	10.442%	$11.3534	$11.35	$11.35	$11.40
Purchase #3	$73.96	8.457%	$80.2148	$80.21	$80.20	$80.20
Purchase #4	$175.51	8.436%	$190.316	$190.32	$190.30	$190.30
Purchase #5	$74.51	10.383%	$82.2464	$82.25	$82.25	$82.20
Purchase #6	$96.87	8.623%	$105.2231	$105.22	$105.20	$105.20
Purchase #7	$30.71	5.114%	$32.2805	$32.28	$32.30	$32.30
7 purchase totals =	$579.26		$629.2357	$629.23	$629.20	$629.20