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	$161.69	13.525%	$183.5586	$183.56	$183.55	$183.60
Purchase #2	$49.61	6.721%	$52.9443	$52.94	$52.95	$52.90
Purchase #3	$71.88	6.129%	$76.2855	$76.29	$76.30	$76.30
Purchase #4	$43.33	6.847%	$46.2968	$46.30	$46.30	$46.30
Purchase #5	$42.60	3.809%	$44.2226	$44.22	$44.20	$44.20
Purchase #6	$233.74	13.765%	$265.9143	$265.91	$265.90	$265.90
Purchase #7	$120.80	5.208%	$127.0913	$127.09	$127.10	$127.10
7 purchase totals =	$723.65		$796.3134	$796.31	$796.30	$796.30