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	$158.25	4.796%	$165.8397	$165.84	$165.85	$165.80
Purchase #2	$127.78	3.289%	$131.9827	$131.98	$132.00	$132.00
Purchase #3	$18.27	13.483%	$20.7333	$20.73	$20.75	$20.70
Purchase #4	$171.66	4.433%	$179.2697	$179.27	$179.25	$179.30
Purchase #5	$62.35	13.861%	$70.9923	$70.99	$71.00	$71.00
Purchase #6	$243.42	3.241%	$251.3092	$251.31	$251.30	$251.30
Purchase #7	$215.81	12.245%	$242.2359	$242.24	$242.25	$242.20
7 purchase totals =	$997.54		$1,062.3628	$1,062.36	$1,062.40	$1,062.30