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	$153.98	11.655%	$171.9264	$171.93	$171.95	$171.90
Purchase #2	$127.72	10.851%	$141.5789	$141.58	$141.60	$141.60
Purchase #3	$230.88	5.450%	$243.463	$243.46	$243.45	$243.50
Purchase #4	$213.79	4.423%	$223.2459	$223.25	$223.25	$223.20
Purchase #5	$25.40	10.857%	$28.1577	$28.16	$28.15	$28.20
Purchase #6	$118.98	11.765%	$132.978	$132.98	$133.00	$133.00
Purchase #7	$192.51	12.371%	$216.3254	$216.33	$216.35	$216.30
7 purchase totals =	$1,063.26		$1,157.6753	$1,157.69	$1,157.75	$1,157.70