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	$118.48	11.321%	$131.8931	$131.89	$131.90	$131.90
Purchase #2	$48.86	10.362%	$53.9229	$53.92	$53.90	$53.90
Purchase #3	$88.70	8.582%	$96.3122	$96.31	$96.30	$96.30
Purchase #4	$118.38	3.139%	$122.0959	$122.10	$122.10	$122.10
Purchase #5	$153.37	13.126%	$173.5013	$173.50	$173.50	$173.50
Purchase #6	$238.78	12.461%	$268.5344	$268.53	$268.55	$268.50
Purchase #7	$240.58	7.402%	$258.3877	$258.39	$258.40	$258.40
7 purchase totals =	$1,007.15		$1,104.6475	$1,104.64	$1,104.65	$1,104.60