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	$174.37	12.547%	$196.2482	$196.25	$196.25	$196.20
Purchase #2	$176.44	3.123%	$181.9502	$181.95	$181.95	$182.00
Purchase #3	$158.32	4.586%	$165.5806	$165.58	$165.60	$165.60
Purchase #4	$55.92	7.704%	$60.2281	$60.23	$60.25	$60.20
Purchase #5	$5.85	8.520%	$6.3484	$6.35	$6.35	$6.30
Purchase #6	$40.75	13.498%	$46.2504	$46.25	$46.25	$46.30
Purchase #7	$78.27	12.816%	$88.3011	$88.30	$88.30	$88.30
7 purchase totals =	$689.92		$744.9070	$744.91	$744.95	$744.90