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	$40.79	5.541%	$43.0502	$43.05	$43.05	$43.10
Purchase #2	$171.51	5.788%	$181.437	$181.44	$181.45	$181.40
Purchase #3	$119.85	9.174%	$130.845	$130.85	$130.85	$130.80
Purchase #4	$231.98	12.639%	$261.3	$261.30	$261.30	$261.30
Purchase #5	$173.32	8.658%	$188.326	$188.33	$188.35	$188.30
Purchase #6	$216.31	3.252%	$223.3444	$223.34	$223.35	$223.30
Purchase #7	$144.38	8.563%	$156.7433	$156.74	$156.75	$156.70
7 purchase totals =	$1,098.14		$1,185.0459	$1,185.05	$1,185.10	$1,184.90