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	$207.47	12.437%	$233.273	$233.27	$233.25	$233.30
Purchase #2	$64.77	10.471%	$71.5521	$71.55	$71.55	$71.60
Purchase #3	$79.97	6.591%	$85.2408	$85.24	$85.25	$85.20
Purchase #4	$181.95	13.689%	$206.8571	$206.86	$206.85	$206.90
Purchase #5	$157.60	9.873%	$173.1598	$173.16	$173.15	$173.20
Purchase #6	$43.69	3.132%	$45.0584	$45.06	$45.05	$45.10
Purchase #7	$242.76	9.769%	$266.4752	$266.48	$266.50	$266.50
7 purchase totals =	$978.21		$1,081.6164	$1,081.62	$1,081.60	$1,081.80