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	$166.39	5.112%	$174.8959	$174.90	$174.90	$174.90
Purchase #2	$204.62	3.276%	$211.3234	$211.32	$211.30	$211.30
Purchase #3	$54.73	8.153%	$59.1921	$59.19	$59.20	$59.20
Purchase #4	$214.34	3.659%	$222.1827	$222.18	$222.20	$222.20
Purchase #5	$198.94	3.238%	$205.3817	$205.38	$205.40	$205.40
Purchase #6	$181.58	9.660%	$199.1206	$199.12	$199.10	$199.10
Purchase #7	$94.93	5.522%	$100.172	$100.17	$100.15	$100.20
7 purchase totals =	$1,115.53		$1,172.2684	$1,172.26	$1,172.25	$1,172.30