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	$235.90	5.522%	$248.9264	$248.93	$248.95	$248.90
Purchase #2	$6.81	5.551%	$7.188	$7.19	$7.20	$7.20
Purchase #3	$51.30	3.354%	$53.0206	$53.02	$53.00	$53.00
Purchase #4	$68.70	3.744%	$71.2721	$71.27	$71.25	$71.30
Purchase #5	$81.29	5.685%	$85.9113	$85.91	$85.90	$85.90
Purchase #6	$98.91	10.333%	$109.1304	$109.13	$109.15	$109.10
Purchase #7	$162.49	6.162%	$172.5026	$172.50	$172.50	$172.50
7 purchase totals =	$705.40		$747.9514	$747.95	$747.95	$747.90