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	$68.96	4.647%	$72.1646	$72.16	$72.15	$72.20
Purchase #2	$170.62	10.268%	$188.1393	$188.14	$188.15	$188.10
Purchase #3	$182.49	12.445%	$205.2009	$205.20	$205.20	$205.20
Purchase #4	$162.30	11.557%	$181.057	$181.06	$181.05	$181.10
Purchase #5	$242.61	5.368%	$255.6333	$255.63	$255.65	$255.60
Purchase #6	$67.32	7.754%	$72.54	$72.54	$72.55	$72.50
Purchase #7	$174.73	4.424%	$182.4601	$182.46	$182.45	$182.50
7 purchase totals =	$1,069.03		$1,157.1952	$1,157.19	$1,157.20	$1,157.20