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	$244.37	5.666%	$258.216	$258.22	$258.20	$258.20
Purchase #2	$61.70	4.259%	$64.3278	$64.33	$64.35	$64.30
Purchase #3	$84.60	5.588%	$89.3274	$89.33	$89.35	$89.30
Purchase #4	$167.61	5.774%	$177.2878	$177.29	$177.30	$177.30
Purchase #5	$156.97	3.311%	$162.1673	$162.17	$162.15	$162.20
Purchase #6	$230.56	3.513%	$238.6596	$238.66	$238.65	$238.70
Purchase #7	$106.92	4.598%	$111.8362	$111.84	$111.85	$111.80
7 purchase totals =	$1,052.73		$1,101.8221	$1,101.84	$1,101.85	$1,101.80