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	$68.83	10.525%	$76.0744	$76.07	$76.05	$76.10
Purchase #2	$250.88	3.304%	$259.1691	$259.17	$259.15	$259.20
Purchase #3	$88.99	8.368%	$96.4367	$96.44	$96.45	$96.40
Purchase #4	$141.83	8.487%	$153.8671	$153.87	$153.85	$153.90
Purchase #5	$86.38	4.123%	$89.9414	$89.94	$89.95	$89.90
Purchase #6	$196.91	8.316%	$213.285	$213.29	$213.30	$213.30
Purchase #7	$122.26	6.645%	$130.3842	$130.38	$130.40	$130.40
7 purchase totals =	$956.08		$1,019.1579	$1,019.16	$1,019.15	$1,019.20