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	$191.33	13.467%	$217.0964	$217.10	$217.10	$217.10
Purchase #2	$28.74	12.159%	$32.2345	$32.23	$32.25	$32.20
Purchase #3	$69.43	4.215%	$72.3565	$72.36	$72.35	$72.40
Purchase #4	$165.96	10.532%	$183.4389	$183.44	$183.45	$183.40
Purchase #5	$150.54	11.490%	$167.837	$167.84	$167.85	$167.80
Purchase #6	$241.86	4.823%	$253.5249	$253.52	$253.50	$253.50
Purchase #7	$158.32	10.255%	$174.5557	$174.56	$174.55	$174.60
7 purchase totals =	$1,006.18		$1,101.0439	$1,101.05	$1,101.05	$1,101.00