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	$245.75	4.540%	$256.9071	$256.91	$256.90	$256.90
Purchase #2	$62.27	5.433%	$65.6531	$65.65	$65.65	$65.70
Purchase #3	$202.29	4.408%	$211.2069	$211.21	$211.20	$211.20
Purchase #4	$94.60	5.259%	$99.575	$99.58	$99.60	$99.60
Purchase #5	$61.85	13.862%	$70.4236	$70.42	$70.40	$70.40
Purchase #6	$67.55	6.676%	$72.0596	$72.06	$72.05	$72.10
Purchase #7	$240.69	8.642%	$261.4904	$261.49	$261.50	$261.50
7 purchase totals =	$975.00		$1,037.3157	$1,037.32	$1,037.30	$1,037.40