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	$130.81	10.448%	$144.477	$144.48	$144.50	$144.50
Purchase #2	$162.69	3.361%	$168.158	$168.16	$168.15	$168.20
Purchase #3	$81.47	12.693%	$91.811	$91.81	$91.80	$91.80
Purchase #4	$210.58	7.248%	$225.8428	$225.84	$225.85	$225.80
Purchase #5	$13.60	7.719%	$14.6498	$14.65	$14.65	$14.60
Purchase #6	$159.25	3.804%	$165.3079	$165.31	$165.30	$165.30
Purchase #7	$196.86	8.842%	$214.2664	$214.27	$214.25	$214.30
7 purchase totals =	$955.26		$1,024.5129	$1,024.52	$1,024.50	$1,024.50