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	$196.56	6.394%	$209.128	$209.13	$209.15	$209.10
Purchase #2	$47.29	10.625%	$52.3146	$52.31	$52.30	$52.30
Purchase #3	$242.31	9.160%	$264.5056	$264.51	$264.50	$264.50
Purchase #4	$222.68	6.520%	$237.1987	$237.20	$237.20	$237.20
Purchase #5	$130.86	11.274%	$145.6132	$145.61	$145.60	$145.60
Purchase #6	$171.43	8.160%	$185.4187	$185.42	$185.40	$185.40
Purchase #7	$160.59	8.180%	$173.7263	$173.73	$173.75	$173.70
7 purchase totals =	$1,171.72		$1,267.9051	$1,267.91	$1,267.90	$1,267.80