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	$107.29	5.290%	$112.9656	$112.97	$112.95	$113.00
Purchase #2	$9.57	10.251%	$10.551	$10.55	$10.55	$10.60
Purchase #3	$67.89	13.457%	$77.026	$77.03	$77.05	$77.00
Purchase #4	$153.46	7.610%	$165.1383	$165.14	$165.15	$165.10
Purchase #5	$73.33	8.530%	$79.585	$79.59	$79.60	$79.60
Purchase #6	$108.27	6.112%	$114.8875	$114.89	$114.90	$114.90
Purchase #7	$101.75	5.702%	$107.5518	$107.55	$107.55	$107.60
7 purchase totals =	$621.56		$667.7052	$667.72	$667.75	$667.80