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	$181.49	4.702%	$190.0237	$190.02	$190.00	$190.00
Purchase #2	$26.76	11.603%	$29.865	$29.87	$29.85	$29.90
Purchase #3	$248.72	6.726%	$265.4489	$265.45	$265.45	$265.40
Purchase #4	$89.62	13.134%	$101.3907	$101.39	$101.40	$101.40
Purchase #5	$134.58	4.173%	$140.196	$140.20	$140.20	$140.20
Purchase #6	$139.83	11.561%	$155.9957	$156.00	$156.00	$156.00
Purchase #7	$239.78	9.324%	$262.1371	$262.14	$262.15	$262.10
7 purchase totals =	$1,060.78		$1,145.0571	$1,145.07	$1,145.05	$1,145.00