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	$94.65	7.694%	$101.9324	$101.93	$101.95	$101.90
Purchase #2	$229.73	3.624%	$238.0554	$238.06	$238.05	$238.10
Purchase #3	$67.68	7.110%	$72.492	$72.49	$72.50	$72.50
Purchase #4	$18.93	5.742%	$20.017	$20.02	$20.00	$20.00
Purchase #5	$90.84	10.347%	$100.2392	$100.24	$100.25	$100.20
Purchase #6	$147.65	4.624%	$154.4773	$154.48	$154.50	$154.50
Purchase #7	$151.69	10.424%	$167.5022	$167.50	$167.50	$167.50
7 purchase totals =	$801.17		$854.7155	$854.72	$854.75	$854.70