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	$156.64	10.155%	$172.5468	$172.55	$172.55	$172.50
Purchase #2	$50.59	4.831%	$53.034	$53.03	$53.05	$53.00
Purchase #3	$168.41	8.388%	$182.5362	$182.54	$182.55	$182.50
Purchase #4	$162.63	10.337%	$179.4411	$179.44	$179.45	$179.40
Purchase #5	$167.42	9.454%	$183.2479	$183.25	$183.25	$183.20
Purchase #6	$63.74	5.651%	$67.3419	$67.34	$67.35	$67.30
Purchase #7	$158.26	9.677%	$173.5748	$173.57	$173.55	$173.60
7 purchase totals =	$927.69		$1,011.7227	$1,011.72	$1,011.75	$1,011.50