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	$111.98	3.456%	$115.85	$115.85	$115.85	$115.90
Purchase #2	$180.55	5.320%	$190.1553	$190.16	$190.15	$190.20
Purchase #3	$224.29	13.353%	$254.2394	$254.24	$254.25	$254.20
Purchase #4	$191.28	7.410%	$205.4538	$205.45	$205.45	$205.50
Purchase #5	$180.87	5.504%	$190.8251	$190.83	$190.85	$190.80
Purchase #6	$32.34	9.457%	$35.3984	$35.40	$35.40	$35.40
Purchase #7	$198.98	9.148%	$217.1827	$217.18	$217.20	$217.20
7 purchase totals =	$1,120.29		$1,209.1047	$1,209.11	$1,209.15	$1,209.20