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	$118.42	7.581%	$127.3974	$127.40	$127.40	$127.40
Purchase #2	$47.67	10.782%	$52.8098	$52.81	$52.80	$52.80
Purchase #3	$121.69	4.636%	$127.3315	$127.33	$127.35	$127.30
Purchase #4	$26.28	3.825%	$27.2852	$27.29	$27.30	$27.30
Purchase #5	$152.83	12.119%	$171.3515	$171.35	$171.35	$171.40
Purchase #6	$185.32	4.819%	$194.2506	$194.25	$194.25	$194.30
Purchase #7	$51.61	9.798%	$56.6667	$56.67	$56.65	$56.70
7 purchase totals =	$703.82		$757.0927	$757.10	$757.10	$757.20