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	$145.55	3.505%	$150.6515	$150.65	$150.65	$150.70
Purchase #2	$28.71	10.108%	$31.612	$31.61	$31.60	$31.60
Purchase #3	$37.40	10.312%	$41.2567	$41.26	$41.25	$41.30
Purchase #4	$90.61	6.270%	$96.2912	$96.29	$96.30	$96.30
Purchase #5	$101.36	13.269%	$114.8095	$114.81	$114.80	$114.80
Purchase #6	$17.46	12.789%	$19.693	$19.69	$19.70	$19.70
Purchase #7	$146.72	12.662%	$165.2977	$165.30	$165.30	$165.30
7 purchase totals =	$567.81		$619.6116	$619.61	$619.60	$619.70