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	$196.27	7.818%	$211.6144	$211.61	$211.60	$211.60
Purchase #2	$68.99	3.264%	$71.2418	$71.24	$71.25	$71.20
Purchase #3	$48.88	8.417%	$52.9942	$52.99	$53.00	$53.00
Purchase #4	$41.36	6.740%	$44.1477	$44.15	$44.15	$44.10
Purchase #5	$222.47	5.123%	$233.8671	$233.87	$233.85	$233.90
Purchase #6	$95.80	8.529%	$103.9708	$103.97	$103.95	$104.00
Purchase #7	$106.51	4.696%	$111.5117	$111.51	$111.50	$111.50
7 purchase totals =	$780.28		$829.3477	$829.34	$829.30	$829.30