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	$146.64	3.481%	$151.7445	$151.74	$151.75	$151.70
Purchase #2	$75.71	10.227%	$83.4529	$83.45	$83.45	$83.50
Purchase #3	$40.58	9.805%	$44.5589	$44.56	$44.55	$44.60
Purchase #4	$48.79	13.555%	$55.4035	$55.40	$55.40	$55.40
Purchase #5	$194.97	7.672%	$209.9281	$209.93	$209.95	$209.90
Purchase #6	$247.47	13.775%	$281.559	$281.56	$281.55	$281.60
Purchase #7	$248.30	12.302%	$278.8459	$278.85	$278.85	$278.80
7 purchase totals =	$1,002.46		$1,105.4928	$1,105.49	$1,105.50	$1,105.50