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	$231.64	7.855%	$249.8353	$249.84	$249.85	$249.80
Purchase #2	$53.28	4.816%	$55.846	$55.85	$55.85	$55.80
Purchase #3	$118.90	10.782%	$131.7198	$131.72	$131.70	$131.70
Purchase #4	$250.64	3.200%	$258.6605	$258.66	$258.65	$258.70
Purchase #5	$24.32	4.591%	$25.4365	$25.44	$25.45	$25.40
Purchase #6	$153.28	7.830%	$165.2818	$165.28	$165.30	$165.30
Purchase #7	$173.36	7.807%	$186.8942	$186.89	$186.90	$186.90
7 purchase totals =	$1,005.42		$1,073.6741	$1,073.68	$1,073.70	$1,073.60