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	$110.26	5.716%	$116.5625	$116.56	$116.55	$116.60
Purchase #2	$195.80	7.336%	$210.1639	$210.16	$210.15	$210.20
Purchase #3	$230.43	6.244%	$244.818	$244.82	$244.80	$244.80
Purchase #4	$228.58	12.241%	$256.5605	$256.56	$256.55	$256.60
Purchase #5	$158.48	6.281%	$168.4341	$168.43	$168.45	$168.40
Purchase #6	$68.27	6.108%	$72.4399	$72.44	$72.45	$72.40
Purchase #7	$35.50	10.470%	$39.2169	$39.22	$39.20	$39.20
7 purchase totals =	$1,027.32		$1,108.1958	$1,108.19	$1,108.15	$1,108.20