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	$182.38	7.532%	$196.1169	$196.12	$196.10	$196.10
Purchase #2	$134.73	13.443%	$152.8418	$152.84	$152.85	$152.80
Purchase #3	$47.47	10.312%	$52.3651	$52.37	$52.35	$52.40
Purchase #4	$138.43	12.428%	$155.6341	$155.63	$155.65	$155.60
Purchase #5	$148.72	11.227%	$165.4168	$165.42	$165.40	$165.40
Purchase #6	$181.91	10.420%	$200.865	$200.87	$200.85	$200.90
Purchase #7	$236.82	4.722%	$248.0026	$248.00	$248.00	$248.00
7 purchase totals =	$1,070.46		$1,171.2423	$1,171.25	$1,171.20	$1,171.20