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	$172.40	13.147%	$195.0654	$195.07	$195.05	$195.10
Purchase #2	$115.91	9.156%	$126.5227	$126.52	$126.50	$126.50
Purchase #3	$151.80	9.270%	$165.8719	$165.87	$165.85	$165.90
Purchase #4	$109.91	12.385%	$123.5224	$123.52	$123.50	$123.50
Purchase #5	$62.88	13.290%	$71.2368	$71.24	$71.25	$71.20
Purchase #6	$94.71	10.410%	$104.5693	$104.57	$104.55	$104.60
Purchase #7	$19.71	3.128%	$20.3265	$20.33	$20.35	$20.30
7 purchase totals =	$727.32		$807.1150	$807.12	$807.05	$807.10