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	$98.50	6.482%	$104.8848	$104.88	$104.90	$104.90
Purchase #2	$10.28	10.346%	$11.3436	$11.34	$11.35	$11.30
Purchase #3	$102.62	11.221%	$114.135	$114.14	$114.15	$114.10
Purchase #4	$158.78	5.493%	$167.5018	$167.50	$167.50	$167.50
Purchase #5	$216.75	7.852%	$233.7692	$233.77	$233.75	$233.80
Purchase #6	$195.41	11.310%	$217.5109	$217.51	$217.50	$217.50
Purchase #7	$150.36	13.829%	$171.1533	$171.15	$171.15	$171.20
7 purchase totals =	$932.70		$1,020.2986	$1,020.29	$1,020.30	$1,020.30