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	$184.57	6.664%	$196.8697	$196.87	$196.85	$196.90
Purchase #2	$142.64	13.646%	$162.1047	$162.10	$162.10	$162.10
Purchase #3	$10.57	9.650%	$11.59	$11.59	$11.60	$11.60
Purchase #4	$230.49	7.595%	$247.9957	$248.00	$248.00	$248.00
Purchase #5	$89.93	12.819%	$101.4581	$101.46	$101.45	$101.50
Purchase #6	$241.62	13.234%	$273.596	$273.60	$273.60	$273.60
Purchase #7	$155.31	6.658%	$165.6505	$165.65	$165.65	$165.70
7 purchase totals =	$1,055.13		$1,159.2647	$1,159.27	$1,159.25	$1,159.40