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	$184.97	7.519%	$198.8779	$198.88	$198.90	$198.90
Purchase #2	$187.55	4.625%	$196.2242	$196.22	$196.20	$196.20
Purchase #3	$101.66	4.402%	$106.1351	$106.14	$106.15	$106.10
Purchase #4	$56.32	9.385%	$61.6056	$61.61	$61.60	$61.60
Purchase #5	$241.82	6.783%	$258.2227	$258.22	$258.20	$258.20
Purchase #6	$150.25	5.330%	$158.2583	$158.26	$158.25	$158.30
Purchase #7	$129.88	13.710%	$147.6865	$147.69	$147.70	$147.70
7 purchase totals =	$1,052.45		$1,127.0103	$1,127.02	$1,127.00	$1,127.00