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	$151.56	7.378%	$162.7421	$162.74	$162.75	$162.70
Purchase #2	$156.60	5.473%	$165.1707	$165.17	$165.15	$165.20
Purchase #3	$47.47	12.348%	$53.3316	$53.33	$53.35	$53.30
Purchase #4	$127.35	10.671%	$140.9395	$140.94	$140.95	$140.90
Purchase #5	$32.42	13.301%	$36.7322	$36.73	$36.75	$36.70
Purchase #6	$224.71	13.376%	$254.7672	$254.77	$254.75	$254.80
Purchase #7	$121.65	4.797%	$127.4856	$127.49	$127.50	$127.50
7 purchase totals =	$861.76		$941.1689	$941.17	$941.20	$941.10