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	$119.71	6.683%	$127.7102	$127.71	$127.70	$127.70
Purchase #2	$12.40	9.224%	$13.5438	$13.54	$13.55	$13.50
Purchase #3	$152.65	12.530%	$171.777	$171.78	$171.80	$171.80
Purchase #4	$240.33	3.535%	$248.8257	$248.83	$248.85	$248.80
Purchase #5	$58.69	4.616%	$61.3991	$61.40	$61.40	$61.40
Purchase #6	$168.91	8.482%	$183.2369	$183.24	$183.25	$183.20
Purchase #7	$213.78	7.743%	$230.333	$230.33	$230.35	$230.30
7 purchase totals =	$966.47		$1,036.8257	$1,036.83	$1,036.90	$1,036.70