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	$98.49	13.645%	$111.929	$111.93	$111.95	$111.90
Purchase #2	$50.85	4.847%	$53.3147	$53.31	$53.30	$53.30
Purchase #3	$81.32	12.740%	$91.6802	$91.68	$91.70	$91.70
Purchase #4	$240.31	8.850%	$261.5774	$261.58	$261.60	$261.60
Purchase #5	$111.26	4.793%	$116.5927	$116.59	$116.60	$116.60
Purchase #6	$219.99	5.420%	$231.9135	$231.91	$231.90	$231.90
Purchase #7	$113.28	12.348%	$127.2678	$127.27	$127.25	$127.30
7 purchase totals =	$915.50		$994.2753	$994.27	$994.30	$994.30