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	$185.43	9.109%	$202.3208	$202.32	$202.30	$202.30
Purchase #2	$63.94	5.764%	$67.6255	$67.63	$67.65	$67.60
Purchase #3	$73.58	12.454%	$82.7437	$82.74	$82.75	$82.70
Purchase #4	$73.92	8.295%	$80.0517	$80.05	$80.05	$80.10
Purchase #5	$144.28	6.468%	$153.612	$153.61	$153.60	$153.60
Purchase #6	$233.85	4.848%	$245.187	$245.19	$245.20	$245.20
Purchase #7	$178.87	3.406%	$184.9623	$184.96	$184.95	$185.00
7 purchase totals =	$953.87		$1,016.5030	$1,016.50	$1,016.50	$1,016.50