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	$76.62	4.753%	$80.2617	$80.26	$80.25	$80.30
Purchase #2	$214.72	4.227%	$223.7962	$223.80	$223.80	$223.80
Purchase #3	$226.40	4.498%	$236.5835	$236.58	$236.60	$236.60
Purchase #4	$86.48	11.311%	$96.2618	$96.26	$96.25	$96.30
Purchase #5	$174.92	9.263%	$191.1228	$191.12	$191.10	$191.10
Purchase #6	$172.95	6.728%	$184.5861	$184.59	$184.60	$184.60
Purchase #7	$90.60	8.605%	$98.3961	$98.40	$98.40	$98.40
7 purchase totals =	$1,042.69		$1,111.0082	$1,111.01	$1,111.00	$1,111.10