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	$114.82	9.528%	$125.76	$125.76	$125.75	$125.80
Purchase #2	$182.58	4.753%	$191.258	$191.26	$191.25	$191.30
Purchase #3	$182.37	3.178%	$188.1657	$188.17	$188.15	$188.20
Purchase #4	$173.96	8.830%	$189.3207	$189.32	$189.30	$189.30
Purchase #5	$101.83	9.326%	$111.3267	$111.33	$111.35	$111.30
Purchase #6	$155.39	9.323%	$169.877	$169.88	$169.90	$169.90
Purchase #7	$240.64	6.120%	$255.3672	$255.37	$255.35	$255.40
7 purchase totals =	$1,151.59		$1,231.0753	$1,231.09	$1,231.05	$1,231.20