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	$144.78	5.490%	$152.7284	$152.73	$152.75	$152.70
Purchase #2	$40.88	11.792%	$45.7006	$45.70	$45.70	$45.70
Purchase #3	$160.61	8.480%	$174.2297	$174.23	$174.25	$174.20
Purchase #4	$167.31	13.406%	$189.7396	$189.74	$189.75	$189.70
Purchase #5	$175.28	4.157%	$182.5664	$182.57	$182.55	$182.60
Purchase #6	$161.84	7.188%	$173.4731	$173.47	$173.45	$173.50
Purchase #7	$89.44	5.154%	$94.0497	$94.05	$94.05	$94.00
7 purchase totals =	$940.14		$1,012.4875	$1,012.49	$1,012.50	$1,012.40