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	$174.58	4.643%	$182.6857	$182.69	$182.70	$182.70
Purchase #2	$101.96	7.328%	$109.4316	$109.43	$109.45	$109.40
Purchase #3	$71.58	12.157%	$80.282	$80.28	$80.30	$80.30
Purchase #4	$13.88	3.604%	$14.3802	$14.38	$14.40	$14.40
Purchase #5	$91.61	5.347%	$96.5084	$96.51	$96.50	$96.50
Purchase #6	$203.72	6.121%	$216.1897	$216.19	$216.20	$216.20
Purchase #7	$37.60	7.618%	$40.4644	$40.46	$40.45	$40.50
7 purchase totals =	$694.93		$739.9420	$739.94	$740.00	$740.00