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	$151.83	13.686%	$172.6095	$172.61	$172.60	$172.60
Purchase #2	$47.96	4.384%	$50.0626	$50.06	$50.05	$50.10
Purchase #3	$156.53	7.465%	$168.215	$168.22	$168.20	$168.20
Purchase #4	$20.49	4.540%	$21.4202	$21.42	$21.40	$21.40
Purchase #5	$229.45	5.571%	$242.2327	$242.23	$242.25	$242.20
Purchase #6	$128.43	7.696%	$138.314	$138.31	$138.30	$138.30
Purchase #7	$211.48	10.548%	$233.7869	$233.79	$233.80	$233.80
7 purchase totals =	$946.17		$1,026.6409	$1,026.64	$1,026.60	$1,026.60