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	$248.69	8.115%	$268.8712	$268.87	$268.85	$268.90
Purchase #2	$28.83	7.801%	$31.079	$31.08	$31.10	$31.10
Purchase #3	$237.71	10.550%	$262.7884	$262.79	$262.80	$262.80
Purchase #4	$211.26	8.217%	$228.6192	$228.62	$228.60	$228.60
Purchase #5	$39.92	13.664%	$45.3747	$45.37	$45.35	$45.40
Purchase #6	$51.60	5.488%	$54.4318	$54.43	$54.45	$54.40
Purchase #7	$118.25	8.385%	$128.1653	$128.17	$128.15	$128.20
7 purchase totals =	$936.26		$1,019.3296	$1,019.33	$1,019.30	$1,019.40