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	$175.70	10.133%	$193.5037	$193.50	$193.50	$193.50
Purchase #2	$174.40	4.290%	$181.8818	$181.88	$181.90	$181.90
Purchase #3	$136.96	13.580%	$155.5592	$155.56	$155.55	$155.60
Purchase #4	$175.51	7.609%	$188.8646	$188.86	$188.85	$188.90
Purchase #5	$60.78	5.432%	$64.0816	$64.08	$64.10	$64.10
Purchase #6	$24.78	13.295%	$28.0745	$28.07	$28.05	$28.10
Purchase #7	$185.28	10.253%	$204.2768	$204.28	$204.30	$204.30
7 purchase totals =	$933.41		$1,016.2422	$1,016.23	$1,016.25	$1,016.40