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	$194.90	6.647%	$207.855	$207.86	$207.85	$207.90
Purchase #2	$202.32	10.163%	$222.8818	$222.88	$222.90	$222.90
Purchase #3	$243.51	4.763%	$255.1084	$255.11	$255.10	$255.10
Purchase #4	$240.91	6.592%	$256.7908	$256.79	$256.80	$256.80
Purchase #5	$29.41	6.536%	$31.3322	$31.33	$31.35	$31.30
Purchase #6	$75.43	9.331%	$82.4684	$82.47	$82.45	$82.50
Purchase #7	$119.27	9.717%	$130.8595	$130.86	$130.85	$130.90
7 purchase totals =	$1,105.75		$1,187.2961	$1,187.30	$1,187.30	$1,187.40