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	$149.69	4.699%	$156.7239	$156.72	$156.70	$156.70
Purchase #2	$155.59	4.336%	$162.3364	$162.34	$162.35	$162.30
Purchase #3	$23.40	4.542%	$24.4628	$24.46	$24.45	$24.50
Purchase #4	$235.31	11.506%	$262.3848	$262.38	$262.40	$262.40
Purchase #5	$116.87	9.320%	$127.7623	$127.76	$127.75	$127.80
Purchase #6	$201.32	9.210%	$219.8616	$219.86	$219.85	$219.90
Purchase #7	$108.57	5.570%	$114.6173	$114.62	$114.60	$114.60
7 purchase totals =	$990.75		$1,068.1491	$1,068.14	$1,068.10	$1,068.20