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	$147.42	4.426%	$153.9448	$153.94	$153.95	$153.90
Purchase #2	$94.96	4.769%	$99.4886	$99.49	$99.50	$99.50
Purchase #3	$35.44	10.539%	$39.175	$39.18	$39.20	$39.20
Purchase #4	$112.46	5.220%	$118.3304	$118.33	$118.35	$118.30
Purchase #5	$79.65	11.860%	$89.0965	$89.10	$89.10	$89.10
Purchase #6	$185.36	8.149%	$200.465	$200.47	$200.45	$200.50
Purchase #7	$48.46	9.754%	$53.1868	$53.19	$53.20	$53.20
7 purchase totals =	$703.75		$753.6871	$753.70	$753.75	$753.70