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	$193.34	6.442%	$205.795	$205.80	$205.80	$205.80
Purchase #2	$47.32	6.176%	$50.2425	$50.24	$50.25	$50.20
Purchase #3	$92.91	12.112%	$104.1633	$104.16	$104.15	$104.20
Purchase #4	$52.48	3.137%	$54.1263	$54.13	$54.15	$54.10
Purchase #5	$124.47	5.873%	$131.7801	$131.78	$131.80	$131.80
Purchase #6	$98.29	7.419%	$105.5821	$105.58	$105.60	$105.60
Purchase #7	$83.30	13.386%	$94.4505	$94.45	$94.45	$94.50
7 purchase totals =	$692.11		$746.1398	$746.14	$746.20	$746.20