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	$231.79	13.457%	$262.982	$262.98	$263.00	$263.00
Purchase #2	$50.52	5.382%	$53.239	$53.24	$53.25	$53.20
Purchase #3	$227.29	6.354%	$241.732	$241.73	$241.75	$241.70
Purchase #4	$54.41	12.441%	$61.1791	$61.18	$61.20	$61.20
Purchase #5	$145.90	7.701%	$157.1358	$157.14	$157.15	$157.10
Purchase #6	$82.26	9.799%	$90.3207	$90.32	$90.30	$90.30
Purchase #7	$59.65	10.560%	$65.949	$65.95	$65.95	$65.90
7 purchase totals =	$851.82		$932.5376	$932.54	$932.60	$932.40