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	$197.69	12.410%	$222.2233	$222.22	$222.20	$222.20
Purchase #2	$72.32	7.473%	$77.7245	$77.72	$77.70	$77.70
Purchase #3	$160.35	13.113%	$181.3767	$181.38	$181.40	$181.40
Purchase #4	$190.74	3.346%	$197.1222	$197.12	$197.10	$197.10
Purchase #5	$118.93	11.275%	$132.3394	$132.34	$132.35	$132.30
Purchase #6	$179.54	9.477%	$196.555	$196.56	$196.55	$196.60
Purchase #7	$151.59	6.279%	$161.1083	$161.11	$161.10	$161.10
7 purchase totals =	$1,071.16		$1,168.4494	$1,168.45	$1,168.40	$1,168.40