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	$218.28	12.255%	$245.0302	$245.03	$245.05	$245.00
Purchase #2	$173.59	6.258%	$184.4533	$184.45	$184.45	$184.50
Purchase #3	$115.49	6.578%	$123.0869	$123.09	$123.10	$123.10
Purchase #4	$196.60	7.538%	$211.4197	$211.42	$211.40	$211.40
Purchase #5	$64.41	5.397%	$67.8862	$67.89	$67.90	$67.90
Purchase #6	$152.82	9.749%	$167.7184	$167.72	$167.70	$167.70
Purchase #7	$145.75	4.562%	$152.3991	$152.40	$152.40	$152.40
7 purchase totals =	$1,066.94		$1,151.9938	$1,152.00	$1,152.00	$1,152.00