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	$148.98	4.470%	$155.6394	$155.64	$155.65	$155.60
Purchase #2	$185.68	3.115%	$191.4639	$191.46	$191.45	$191.50
Purchase #3	$135.97	10.681%	$150.493	$150.49	$150.50	$150.50
Purchase #4	$75.62	7.619%	$81.3815	$81.38	$81.40	$81.40
Purchase #5	$128.49	10.688%	$142.223	$142.22	$142.20	$142.20
Purchase #6	$90.31	11.511%	$100.7056	$100.71	$100.70	$100.70
Purchase #7	$114.65	11.236%	$127.5321	$127.53	$127.55	$127.50
7 purchase totals =	$879.70		$949.4385	$949.43	$949.45	$949.40