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	$162.30	7.422%	$174.3459	$174.35	$174.35	$174.30
Purchase #2	$37.29	13.468%	$42.3122	$42.31	$42.30	$42.30
Purchase #3	$30.44	10.626%	$33.6746	$33.67	$33.65	$33.70
Purchase #4	$228.33	8.222%	$247.1033	$247.10	$247.10	$247.10
Purchase #5	$244.78	9.427%	$267.8554	$267.86	$267.85	$267.90
Purchase #6	$101.39	3.719%	$105.1607	$105.16	$105.15	$105.20
Purchase #7	$216.63	11.447%	$241.4276	$241.43	$241.45	$241.40
7 purchase totals =	$1,021.16		$1,111.8797	$1,111.88	$1,111.85	$1,111.90